Evoqua Water Technologies (AQUA) 10-Q 7 Feb 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information Statement - shares	3 Months Ended
	Dec. 31, 2017	Feb. 01, 2018
Document Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2,018
Entity Registrant Name	EVOQUA WATER TECHNOLOGIES CORP.
Entity Central Index Key	1,604,643
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		113,264,493

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
ASSETS
Current assets	$ 520,436	$ 512,240
Cash and cash equivalents	80,250	59,254
Receivables, net	226,719	245,248
Inventories, net	128,306	120,047
Cost and earnings in excess of billings on uncompleted contracts	65,038	66,814
Prepaid and other current assets	19,287	20,046
Income tax receivable	836	831
Property, plant, and equipment, net	281,507	280,043
Goodwill	320,927	321,913
Intangible assets, net	329,568	333,746
Deferred income taxes	2,968	2,968
Other non‑current assets	23,503	22,399
Total assets	1,478,909	1,473,309
LIABILITIES AND EQUITY
Current liabilities	263,746	291,899
Accounts payable	114,489	114,932
Current portion of debt	11,033	11,325
Billings in excess of costs incurred	36,511	27,124
Product warranties	9,807	11,164
Accrued expenses and other liabilities	88,793	121,923
Income tax payable	3,113	5,431
Non‑current liabilities	862,441	964,835
Long‑term debt	777,900	878,524
Product warranties	6,497	6,110
Other non‑current liabilities	68,884	67,673
Deferred income taxes	9,160	12,528
Total liabilities	1,126,187	1,256,734
Commitments and Contingent Liabilities (Note 17)
Shareholders’ equity
Common stock, par value $0.01: authorized 1,000,000 shares; issued 105,359 shares, outstanding 104,949 shares at September 30, 2017; issued 113,692 shares, outstanding 113,264 shares at December 31, 2017.	1,137	1,054
Treasury stock: 410 shares at September 30, 2017 and 428 shares at December 31, 2017	(2,837)	(2,607)
Additional paid‑in capital	529,120	388,986
Retained deficit	(173,719)	(170,006)
Accumulated other comprehensive loss, net of tax	(6,324)	(5,989)
Total Evoqua Water Technologies Corp. equity	347,377	211,438
Non‑controlling interest	5,345	5,137
Total shareholders’ equity	352,722	216,575
Total liabilities and shareholders’ equity	$ 1,478,909	$ 1,473,309

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets Parenthetical - $ / shares	Dec. 31, 2017	Sep. 30, 2017
Statement of Financial Position [Abstract]
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock issued (in shares)	113,692,000	105,359,000
Common stock outstanding (in shares)	113,264,000	104,964,000
Treasury stock (in shares)	410,000	410,000

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Revenues [Abstract]
Revenue from product sales and services	$ 297,051	$ 279,872
Cost of Revenue [Abstract]
Cost of product sales and services	(208,672)	(196,813)
Gross Profit	88,379	83,059
Operating Expenses [Abstract]
General and administrative expense	(39,064)	(49,186)
Sales and marketing expense	(34,241)	(35,093)
Research and development expense	(4,653)	(5,005)
Other operating income (expense)	(593)	683
Interest expense	(17,243)	(14,753)
Loss before income taxes	(7,415)	(20,295)
Income tax benefit (expense)	4,410	7,095
Net (loss) income	(3,005)	(13,200)
Net income attributable to non‑controlling interest	708	399
Net (loss) income attributable to Evoqua Water Technologies Corp.	$ (3,713)	$ (13,599)
Basic (loss) earnings per common share (in dollars per share)	$ (0.03)	$ (0.13)
Diluted (loss) earnings per common share (in dollars per share)	$ (0.03)	$ (0.13)

Unaudited Condensed Consolidat5

Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (3,005)	$ (13,200)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	(335)	3,219
Less: Comprehensive income attributable to non‑controlling interest	708	399
Comprehensive (loss) income attributable to Evoqua Water Technologies Corp.	$ (4,048)	$ (10,380)

Unaudited Condensed Consolidat6

Unaudited Condensed Consolidated Statements of Changes in Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid‑in Capital	Retained Deficit	Accumulated Other Comprehensive Loss	Non‑controlling Interest
Common stock issued at the beginning of the period (shares) at Sep. 30, 2016		104,495
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2016	$ 203,935	$ 1,045	$ (1,133)	$ 381,223	$ (172,169)	$ (10,671)	$ 5,640
Treasury stock, balance at the beginning of the period (in shares) at Sep. 30, 2016			245
Equity based compensation expense	466			466
Issuance of common stock (in shares)		568
Issuance of common stock	4,058	$ 6		4,052
Stock repurchases (shares)			15
Stock repurchases	(120)		$ (120)
Dividends paid to non‑controlling interest	(750)						(750)
Net loss	(13,200)				(13,599)		399
Other comprehensive loss	3,219					3,219
Common stock issued at the end of the period (shares) at Dec. 31, 2016		105,063
Stockholders' equity, balance at the end of the period at Dec. 31, 2016	$ 197,608	$ 1,051	$ (1,253)	385,741	(185,768)	(7,452)	5,289
Treasury stock, balance at the end of the period (in shares) at Dec. 31, 2016			260
Common stock issued at the beginning of the period (shares) at Sep. 30, 2017	105,359	105,359
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2017	$ 216,575	$ 1,054	$ (2,607)	388,986	(170,006)	(5,989)	5,137
Treasury stock, balance at the beginning of the period (in shares) at Sep. 30, 2017	410		410
Equity based compensation expense	$ 2,612			2,612
Issuance of common stock (in shares)		8,333
Issuance of common stock	137,605	$ 83		137,522
Stock repurchases (shares)			18
Stock repurchases	(230)		$ (230)
Dividends paid to non‑controlling interest	(500)						(500)
Net loss	(3,005)				(3,713)		708
Other comprehensive loss	$ (335)					(335)
Common stock issued at the end of the period (shares) at Dec. 31, 2017	113,692	113,692
Stockholders' equity, balance at the end of the period at Dec. 31, 2017	$ 352,722	$ 1,137	$ (2,837)	$ 529,120	$ (173,719)	$ (6,324)	$ 5,345
Treasury stock, balance at the end of the period (in shares) at Dec. 31, 2017	410		428

Unaudited Condensed Consolidat7

Unaudited Condensed Consolidated Statements of Changes in Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (3,005)	$ (13,200)
Reconciliation of net loss to cash flows from operating activities:
Depreciation and amortization	19,883	18,647
Amortization of deferred financing costs (includes $2,075 and $2,944 write off of deferred financing fees)	3,842	3,573
Deferred income taxes	(3,088)	(7,064)
Share based compensation	2,612	466
(Loss) gain on sale of property, plant and equipment	182	(464)
Foreign currency losses (gains) on intracompany loans	(1,583)	7,485
Changes in assets and liabilities
Accounts receivable	18,864	(11,988)
Inventories	(8,259)	(6,623)
Cost and earnings in excess of billings on uncompleted contracts	1,905	5,680
Prepaids and other current assets	938	(1,344)
Accounts payable	(513)	(14,765)
Accrued expenses and other liabilities	(32,810)	(10,677)
Billings in excess of costs incurred	9,313	1,467
Income taxes	(2,341)	(1,831)
Other non‑current assets and liabilities	(359)	1,809
Net cash (used in) provided by operating activities	5,581	(28,829)
Investing activities
Purchase of property, plant and equipment	(15,257)	(13,603)
Proceeds from sale of property, plant and equipment	387	746
Acquisitions, net of cash acquired of $0	0	(10,730)
Net cash used in investing activities	(14,870)	(23,587)
Financing activities
Issuance of debt	0	150,000
Capitalized deferred issuance costs related to refinancing	(1,792)	(3,928)
Borrowings under credit facility	6,000	15,000
Repayment of debt	(108,663)	(111,358)
Repayment of capital lease obligation	(2,283)	(2,113)
Proceeds from issuance of common stock	137,605	4,052
Stock repurchases	(230)	(120)
Distribution to non‑controlling interest	(500)	(750)
Net cash provided by financing activities	30,137	50,783
Effect of exchange rate changes on cash	148	2,852
Change in cash and cash equivalents	20,996	1,219
Cash and cash equivalents
Beginning of period	59,254	50,362
End of period	80,250	51,581
Supplemental disclosure of cash flow information
Cash paid for taxes	186	1,237
Cash paid for interest	10,749	10,450
Non‑cash investing and financing activities
Capital lease transactions	$ 2,336	$ 392

Unaudited Condensed Consolidat8

Unaudited Condensed Consolidated Statements of Changes in Cash Flows (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Deferred finance costs	$ 2,944	$ 2,075
Net of cash acquired	$ 0	$ 0

Description of the Company and

Description of the Company and Basis of Presentation	3 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Company and Basis of Presentation	Description of the Company and Basis of Presentation Background Evoqua Water Technologies Corp. was incorporated on October 7, 2013. On January 15, 2014, Evoqua Water Technologies Corp., acquired through its wholly owned entities, EWT Holdings II Corp. and EWT Holdings III Corp. (a/k/a Evoqua Water Technologies), all of the outstanding shares of Siemens Water Technologies, a group of legal entity businesses formerly owned by Siemens AG (Siemens). The stock purchase closed on January 15, 2014 and was effective January 16, 2014 (the Acquisition). The stock purchase price, net of cash received, was approximately $730,577 . On November 6, 2017, the Company completed its initial public offering (“IPO”), pursuant to which an aggregate of 27,777 shares of common stock were sold, of which 8,333 were sold by the Company and 19,444 were sold by the selling shareholders, with a par value of $ 0.01 per share. After underwriting discounts and commissions, the Company received net proceeds from the IPO of approximately $137,605 . The Company used a portion of these proceeds to repay $104,936 of indebtedness (including accrued and unpaid interest) under our senior secured first lien term loan facility and the remainder for general corporate purposes. The Company did not receive any proceeds from the sale of shares by the selling stockholders. On November 7, 2017, the selling stockholders sold an additional 4,167 shares of common stock as a result of the exercise in full by the underwriters of an option to purchase additional shares. Evoqua Water Technologies Corp. and subsidiaries will be referred to herein as “the Company” or “EWT”. The Business EWT provides a wide range of product brands and advanced water and wastewater treatment systems and technologies, as well as mobile and emergency water supply solutions and service contract options through its segment branch network. Headquartered in Pittsburgh, Pennsylvania, EWT is a multi‑national corporation with operations in the United States, Canada, the United Kingdom, the Netherlands, Italy, Germany, Australia, China, and Singapore. The Company is organizationally structured into three reportable segments for the purpose of making operational decisions and assessing financial performance: (i) Industrial, (ii) Municipal and (iii) Products. Basis of Presentation The accompanying Unaudited Condensed Consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP). All intracompany transactions have been eliminated. The unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such SEC rules. We believe that the disclosures made are adequate to make the information presented not misleading. We consistently applied the accounting policies described in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017 , as filed with the SEC on December 4, 2017 (“ 2017 Annual Report”), in preparing these unaudited condensed consolidated financial statements, with the exception of accounting standard updates described in Note 2. These condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes included in our 2017 Annual Report.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Fiscal Year The Company’s fiscal year ends on September 30. Use of Estimates The unaudited condensed consolidated financial statements have been prepared in conformity with U.S. GAAP and require management to make estimates and assumptions. These assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Estimates and assumptions are used for, but not limited to: (i) revenue recognition; (ii) allowance for doubtful accounts; (iii) inventory valuation, asset valuations, impairment, and recoverability assessments; (iv) depreciable lives of assets; (v) useful lives of intangible assets; (vi) income tax reserves and valuation allowances; and (vii) product warranty and litigation reserves. Estimates are revised as additional information becomes available. Actual results could differ from these estimates. Cash and Cash Equivalents Cash and cash equivalents are liquid investments with an original maturity of three or fewer months when purchased. Accounts Receivable Receivables are primarily comprised of uncollected amounts owed to us from transactions with customers and are presented net of allowances for doubtful accounts. Allowances are estimated based on historical write‑offs and the economic status of customers. The Company considers a receivable delinquent if it is unpaid after the term of the related invoice has expired. Write‑offs are recorded at the time all collection efforts have been exhausted. Inventories Inventories are stated at the lower of cost or market, where cost is generally determined on the basis of an average or first‑in, first‑out (FIFO) method. Production costs comprise direct material and labor and applicable manufacturing overheads, including depreciation charges. The Company regularly reviews inventory quantities on hand and writes off excess or obsolete inventory based on estimated forecasts of product demand and production requirements. Manufacturing operations recognize cost of product sales using standard costing rates with overhead absorption which generally approximates actual cost. Property, Plant, and Equipment Property, plant, and equipment is valued at cost less accumulated depreciation and impairment losses. If the costs of certain components of an item of property, plant, and equipment are significant in relation to the total cost of the item, they are accounted for and depreciated separately. Depreciation expense is recognized using the straight‑line method. Useful lives are reviewed annually and, if expectations differ from previous estimates, adjusted accordingly. Estimated useful lives for major classes of depreciable assets are as follows: Asset Class Estimated Useful Life Machinery and equipment 3 to 20 years Buildings and improvements 10 to 40 years Leasehold improvements are depreciated over the shorter of their estimated useful life or the term of the lease. Costs related to maintenance and repairs that do not extend the assets’ useful life are expensed as incurred. Goodwill and Other Intangible Assets Goodwill represents purchase consideration paid in a business combination that exceeds the value assigned to the net assets of acquired businesses. Other intangible assets consist of customer‑related intangibles, proprietary technology, software, trademarks and other intangible assets. The Company amortizes intangible assets with definite useful lives on a straight‑line basis over their respective estimated economic lives which range from 1 to 26 years. The Company reviews goodwill to determine potential impairment annually during the fourth quarter of our fiscal year, or more frequently if events and circumstances indicate that the asset might be impaired. Impairment testing for goodwill is performed at a reporting unit level. We have determined that we have four reporting units. Our quantitative impairment testing utilizes both a market (guideline public company) and income (discounted cash flows) method for determining fair value. In estimating the fair value of the reporting unit utilizing a discounted cash flow (“DCF”) valuation technique, we incorporate our judgment and estimates of future cash flows, future revenue and gross profit growth rates, terminal value amount, capital expenditures and applicable weighted‑average cost of capital used to discount these estimated cash flows. The estimates and projections used in the estimate of fair value are consistent with our current budget and long‑range plans, including anticipated change in market conditions, industry trend, growth rates and planned capital expenditures, among other considerations. Impairment of Long‑Lived Assets Long‑lived assets, such as property, plant, and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. Recoverability of the asset or asset group is measured by comparison of its carrying amount to undiscounted future net cash flows the asset or asset group is expected to generate. If the carrying amount of an asset or asset group is not recoverable, the Company recognizes an impairment loss based on the excess of the carrying amount of the asset or asset group over its respective fair value which is generally determined as the present value of estimated future cash flows or as the appraised value. Debt Issuance Costs and Debt Discounts Debt issuance costs are capitalized and amortized over the contractual term of the underlying debt using the straight line method which approximates the effective interest method. Debt discounts and lender arrangement fees deducted from the proceeds have been included as a component of the carrying value of debt and are being amortized to interest expense using the effective interest method. Amortization of debt issuance costs and debt discounts/premiums included in interest expense were $1,498 and $848 for the three months ended December 31, 2016 and 2017 , respectively. In October of 2016, the Company wrote off $ 2,075 of deferred financing fees related to the extinguishment of debt and incurred another $481 of fees related to a tack-on financing the Company completed on October 28, 2016. In November of 2017, the Company wrote off $ 1,844 of deferred financing fees related to a $100,000 prepayment of debt, then subsequently wrote off another $ 1,150 of fees in December of 2017 due to refinancing its Term loan. The Company incurred another $2,131 of fees as a result of the December refinancing. Revenue Recognition Sales of goods and services are recognized when persuasive evidence of an arrangement exists, the price is fixed or determinable, collectability is reasonably assured and delivery has occurred or services have been rendered. For sales of aftermarket parts or products with a low level of customization and engineering time, the Company recognizes revenues at the time title and risks and rewards of ownership pass, which is generally when products are shipped or delivered to the customer as the Company has no obligation for installation. Sales of short‑term service arrangements are recognized as the services are performed, and sales of long‑term service arrangements are typically recognized on a straight‑line basis over the life of the agreement. For certain arrangements where there is significant customization to the product, the Company recognizes revenue under the provisions of Accounting Standards Codification (ASC) 605-35, Revenue Recognition – Construction-Type and Production-Type Contracts. These products include large capital water treatment projects, systems and solutions for municipal and industrial applications. Revenues from construction-type contracts are generally recognized under the percentage-of-completion method, based on the input of costs incurred to date as a percentage of total estimated contract costs. The nature of the contracts is generally fixed price with milestone billings. Approximately $47,063 and $59,387 of revenues from construction-type contracts were recognized on the percentage-of-completion method during the three months ended December 31, 2016 and 2017 , respectively. Contract revenues and cost estimates are reviewed and revised quarterly at a minimum and the cumulative effect of such adjustments are recognized in current operations. The amount of such adjustments have not been material. Cost and earnings in excess of billings under construction‑type arrangements are recorded when contracts have net asset balances where contract costs plus recognized profits less recognized losses exceed progress billings. Billings in excess of costs incurred are recorded when contract progress billings exceed costs and recognized profit less recognized losses. Approximately $8,792 and $6,383 of revenues from construction-type contracts were recognized on a completed contract method, which is typically when the product is delivered and accepted by the customer, during the three months ended December 31, 2016 and 2017 , respectively. The completed contract method is principally used when the contract is short in duration (generally less than twelve months) and where results of operations would not vary materially from those resulting from the use of the percentage-of-completion method. Product Warranties Accruals for estimated expenses related to warranties are made at the time products are sold and are recorded as a component of Cost of product sales in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss. The estimated warranty obligation is based on product warranty terms offered to customers, ongoing product failure rates, material usage and service delivery costs expected to be incurred in correcting a product failure, as well as specific obligations for known failures and other currently available evidence. The Company assesses the adequacy of the recorded warranty liabilities on a regular basis and adjusts amounts as necessary. Shipping and Handling Cost Shipping and handling costs are included as a component of cost of sales. Income Taxes The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are provided against deferred tax assets when it is deemed more likely than not that some portion or all of the deferred tax asset will not be realized within a reasonable time period. We assess tax positions using a two‑step process. A tax position is recognized if it meets a more‑likely‑than‑not threshold, and is measured at the largest amount of benefit that is greater than 50.0% percent of being realized. Uncertain tax positions are reviewed each balance sheet date. Sales Taxes Upon collection of sales tax from revenue, the amount of sales tax is placed into an accrued liability account. This liability is then relieved when the payment is sent to the proper government jurisdiction. Foreign Currency Translation and Transactions The functional currency for the international subsidiaries is the local currency. Assets and liabilities are translated into U.S. Dollars using current rates of exchange, while revenues and expenses are translated at the weighted‑average exchange rate for the period. The resulting translation adjustments are recorded in other comprehensive income/loss within shareholders equity. Foreign currency transaction (gains) losses aggregated $(7,245) and $1,384 for the fiscal three months ended December 31, 2016 and 2017 , respectively, and are primarily included in General and administrative expenses in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income . Research and Development Costs Research and development costs are expensed as incurred. The Company recorded $5,005 and $4,653 of costs for the three months ended December 31, 2016 and 2017 , respectively. Equity‑based Compensation The Company measures the cost of awards of equity instruments to employees based on the grant‑date fair value of the award. Prior to our IPO, given the absence of a public trading market for our common stock, the fair value of the common stock underlying our share‑based awards was determined by our board, with input from management, in each case using the income and market valuation approach. Stock options are granted with exercise prices equal to or greater than the estimated fair market value on the date of grant as authorized by our compensation committee. The grant‑date fair value is determined using the Black‑Scholes model. The fair value, net of estimated forfeitures, is amortized as compensation cost on a straight‑line basis over the vesting period primarily as a component of General and administrative expenses. The Company issued 1,197 shares of common stock, with an aggregate value of $25,000 , to certain employees as restricted stock unit awards made in connection with the IPO. The fair value of such awards was based on the closing price of the Company's stock as of the IPO date and the value will be amortized as compensation expense on a straight-line basis over the vesting period, which is upon the second anniversary of the IPO. Earnings per Share Basic earnings per common share is computed based on the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed based on the weighted average number of shares of common stock, plus the effect of diluted potential common shares outstanding during the period using the treasury stock method. Diluted potential common shares include outstanding stock options. Retirement Benefits The Company applies, ASC Topic 715, Compensation—Retirement Benefits , which requires the recognition in pension obligations and accumulated other comprehensive income of actuarial gains or losses, prior service costs or credits and transition assets or obligations that have previously been deferred. The determination of retirement benefit pension obligations and associated costs requires the use of actuarial computations to estimate participant plan benefits to which the employees will be entitled. The significant assumptions primarily relate to discount rates, expected long‑term rates of return on plan assets, rate of future compensation increases, mortality, years of service, and other factors. The Company develops each assumption using relevant experience in conjunction with market‑related data for each individual country in which such plans exist. All actuarial assumptions are reviewed annually with third‑party consultants and adjusted as necessary. For the recognition of net periodic postretirement cost, the calculation of the expected return on plan assets is generally derived by applying the expected long‑term rate of return on the market‑related value of plan assets. The fair value of plan assets is determined based on actual market prices or estimated fair value at the measurement date. Treated Water Outsourcing The following provides a summary of Treated Water Outsourcing (“TWO”), a joint venture between the Company and Nalco Water, an Ecolab company in which the Company holds a 50% partnership interest, as of September 30, and December 31, 2017 , respectively. As the Company is obligated to absorb all risk of loss up to 100% of the joint venture partner's equity, TWO is fully consolidated within the Company's consolidated financial statements under ASC 810, Consolidation . The Company has not provided additional financial support to this entity which it is not contractually required to provide, and the Company does not have the ability to use the assets of TWO to settle obligations of the Company’s other subsidiaries. September 30, 2017 December 31, 2017 Current assets (including cash of $1,907 and $3,033) $ 12,006 $ 9,665 Property, plant and equipment 6,107 5,704 Goodwill 2,206 2,206 Other noncurrent assets 2,735 — Total liabilities (12,781 ) (6,885 ) Three Months Ended December 31, 2016 2017 Total revenues $ 4,071 $ 5,989 Total operating expenses (3,272 ) (4,574 ) Income from operations $ 799 $ 1,415 Recent Accounting Pronouncements Accounting Pronouncements Not Yet Adopted In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) . ASU No. 2014-09 clarifies the principles for recognizing revenue when an entity either enters into a contract with customers to transfer goods or services or enters into a contract for the transfer of non-financial assets. ASU 2014-09 may be adopted using either of two acceptable methods: (1) retrospective adoption to each prior period presented with the option to elect certain practical expedients; or (2) adoption with the cumulative effect recognized at the date of initial application and providing certain disclosures. To assess at which time revenue should be recognized, an entity should use the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The standard is effective for the Company for the quarter ending December 31, 2018. The Company has completed their first phase of adopting this standard, which was to identify the potential differences that will result from applying the new revenue recognition standard to the Company's contracts with its customers, and has begun the second step of reviewing their contracts to determine the impact of adopting the standard. At this time, the Company is not yet able to estimate the anticipated impact to the Condensed Consolidated financial statements. The Company is also evaluating the new disclosures required by the standard to determine what additional information will need to be disclosed. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . ASU No. 2016-02 requires recognition of operating leases as lease assets and liabilities on the balance sheet, and disclosure of key information about leasing arrangements. ASU No. 2016-02 will be effective retrospectively for the Company for the quarter ending December 31, 2019, with early adoption permitted. The Company is currently assessing the impact adoption of this guidance will have on the Company's Consolidated financial statements. In August 2016, the FASB issued ASU 2016‑15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) . This new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU No. 2016‑15 will be effective for the Company for the quarter ending December 31, 2018, with early adoption permitted. The guidance should be applied retrospectively to all periods presented, unless deem impracticable, in which case prospective application is permitted. The Company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. In October 2016, the FASB issued ASU 2016-17 , Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . The purpose of this update is to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The ASU requires the tax effects of all intra-entity sales of assets other than inventory to be recognized in the period in which the transaction occurs. The guidance will be effective for the Company for the quarter ending December 31, 2018 with early adoption permitted but only in the first interim period of a fiscal year. The changes are required to be applied by means of a cumulative-effect adjustment recorded in retained earnings as of the beginning of the fiscal year of adoption. The Company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. In February 2017, the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires the disaggregation of the service cost component from other components of net periodic benefit cost, clarifies how to present the service cost component and other components of net benefit costs in the Statements of Consolidated Operations and allows only the service cost component of net benefit costs to be eligible for capitalization. This ASU is effective for the Company for the quarter ending December 31, 2018. Adoption will be applied on a retrospective basis for the presentation of all components of net periodic benefit costs and on a prospective basis for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The company is currently evaluating the impact this guidance will have on the Consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU 2017‑09, Scope of Modification Accounting , which amended Accounting Standards Code Topic 718. FASB issued ASU 2017‑09 to reduce the cost and complexity when applying Topic 718 and standardize the practice of applying Topic 718 to financial reporting. The ASU was not developed to fundamentally change the definition of a modification, but instead to provide guidance for what changes would qualify as a modification. ASU No. 2017‑09 will be effective for us for the quarter ending December 31, 2018. The company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. Accounting Pronouncements Recently Adopted The Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends ASC Topic 718, Compensation – Stock Compensation during the three months ended December 31, 2017. The ASU includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The adoption of this ASU did not have a significant impact on the Company's Consolidated financial statements. In January 2017, the FASB issued ASU 2017‑04, Simplifying the Test for Goodwill Impairment . This ASU simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures goodwill impairment loss by comparing the implied value of a reporting unit’s goodwill with the carrying amount of that goodwill. The amendments in this ASU are effective for the Company for the quarter ending December 31, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. ASU 2017-04 was early adopted by the Company for the year beginning October 1, 2017 and did not have a material impact on the Company's Consolidated financial statements.

Acquisitions and Divestitures

Acquisitions and Divestitures	3 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisitions and Divestitures	Acquisitions and Divestitures Acquisitions support the Company's strategy of delivering a broad solutions portfolio with robust technology across multiple geographies and end markets. The Company did not make any acquisitions or divestitures during the three months ended December 31, 2017. The following acquisitions were made during the fiscal year ended September 30, 2017 : On November 1, 2016, the Company acquired essentially all of the assets of Environmental Treatment Services, Inc. (ETS), a leading provider of engineered solutions to the industrial wastewater market based in Acworth, GA for $10,730 . ETS had ten employees as of the date of acquisition. The Company incurred approximately $16 of acquisition costs, which are included in General and administrative expenses. ETS was acquired to support the Company’s growth plan and is included within the Industrial segment of the Company. On May 9, 2017, the Company acquired the assets of Noble Water Technologies, a leader in high purity water systems and service, located in Dallas, TX for $7,634 ; $5,915 cash at closing in addition to earn out payments over the next twelve months. Included in consideration is $1,719 , which represents the fair value of the earn outs at the date of the acquisition related to customer retention, with a maximum earn out payment of $2,366 . The Company incurred approximately $116 of acquisition costs, which are included in General and administrative expenses. Noble’s results are included within the Industrial segment of the Company. On June 30, 2017, the Company acquired ADI Systems North America Inc., Geomembrane Technologies Inc., and Lange Containment Systems, Inc. (collectively, ‘‘ADI’’) from ADI Group Inc. for a total of CAD 72,220 ( $55,558 ); CAD 67,320 ( $51,785 ) cash at closing and the fair value of the earn out payments of CAD 4,900 ( $3,773 ) at the date of acquisition. The cash paid at closing was initially funded through borrowings under the credit facility, which was subsequently paid off through the August 8, 2017 First lien facility amendment. The maximum amount payable under the earn outs is CAD 7,480 ( $5,760 ) if certain performance metrics are achieved over a period of twenty-four months. The three are world leaders in wastewater solutions for industrial and manufacturing applications, primarily based in Fredericton, New Brunswick. ADI offers a wide range of technologies tailored to its customer base around the world in anaerobic digestion, aerobic treatment, and biogas treatment. They also provide green energy recovery and water reuse technologies as well as industrial wastewater cover liners and containment systems. Combined, ADI has more than 260 customers in 35 countries. ADI’s results are included within the Industrial segment of the Company. The Company incurred approximately $109 of acquisition costs, which are included in General and administrative expenses. On June 30, 2017, the Company acquired Olson Irrigation Systems, a leading designer and producer of filters and irrigation components for the agriculture and industrial markets, based in Santee, California, for $9,406 . Olson is part of the Company’s Products segment and will help the business build upon its leadership in filtration serving a broad range of industrial applications. The Company incurred approximately $140 of acquisition costs, which are included in General and administrative expenses. Pro forma results for acquisitions completed in fiscal 2017 were determined to not be material. The opening balance sheet for the acquisitions is summarized as follows. The opening balance sheets for ETS and Noble are considered final as of December 31, 2017. The Company is still reviewing the opening balance sheets for ADI and Olson and expects to be complete by June 30, 2018. ETS Noble ADI Olson Total Current Assets $ 782 $ 567 $ 10,721 $ 1,730 $ 13,800 Property, plant and equipment 376 390 719 841 2,326 Goodwill 5,650 3,576 39,365 3,813 52,404 Other intangible assets 3,953 3,370 12,594 3,456 23,373 Other noncurrent assets — — 1,971 — 1,971 Total asset acquired 10,761 7,903 65,370 9,840 93,874 Total liabilities assumed (31 ) (269 ) (9,812 ) (434 ) (10,546 ) Net assets acquired $ 10,730 $ 7,634 $ 55,558 $ 9,406 $ 83,328

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurements As of September 30, and December 31, 2017 , the fair values of cash and cash equivalents, accounts receivable and accounts payable approximate carrying values due to the short maturity of these items. The Company measures the fair value of pension plan assets and liabilities, deferred compensation and plan assets and liabilities on a recurring basis pursuant to ASC Topic 820. ASC Topic 820 establishes a three‑tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1: Quoted prices for identical instruments in active markets. Level 2: Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model‑derived valuations whose inputs are observable or whose significant value driver is observable. Level 3: Unobservable inputs in which little or no market data is available, therefore requiring an entity to develop its own assumptions. The following table presents the Company’s financial assets and liabilities at fair value. The fair values related to the pension assets are determined using net asset value (NAV) as a practical expedient, or by information categorized in the fair value hierarchy level based on the inputs used to determine fair value. The reported carrying amounts of deferred compensation assets and liabilities and debt approximate their fair values. The Company uses interest rates and other relevant information generated by market transactions involving similar instruments to fair value these assets and liabilities, therefore all are classified as Level 2 within the valuation hierarchy. Net Asset Value Quoted Market Significant Other Significant As of September 30, 2017 Assets: Pension plan Cash $ — $ 16,024 $ — $ — Government Securities 3,206 — — — Liability Driven Investment 2,754 — — — Guernsey Unit Trust 932 — — — Global Absolute Return 2,139 — — — Deferred compensation plan assets Trust Assets — 2,146 — — Insurance — — 17,396 — Liabilities: Pension plan — — (34,803 ) — Deferred compensation plan liabilities — — (21,159 ) — Long‑term debt — — (912,471 ) — As of December 31, 2017 Assets: Pension plan Cash $ — $ 16,139 $ — $ — Government Securities 3,073 — — — Liability Driven Investment 3,360 — — — Guernsey Unit Trust 950 — — — Global Absolute Return 2,198 — — — Deferred compensation plan assets Trust Assets — 1,926 — — Insurance — — 17,935 — Liabilities: Pension plan — — (34,803 ) — Deferred compensation plan liabilities — — (22,615 ) — Long‑term debt — — (807,473 ) — The pension plan assets and liabilities and deferred compensation assets and liabilities are included in other non-current assets and other non-current liabilities at September 30 and December 31, 2017 .

Accounts Receivable

Accounts Receivable	3 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Accounts receivable	Accounts Receivable Accounts receivable are summarized as follows: September 30, 2017 December 31, 2017 Accounts Receivable $ 248,742 $ 230,505 Allowance for Doubtful Accounts (3,494 ) (3,786 ) $ 245,248 $ 226,719

Inventories

Inventories	3 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories	Inventories The major classes of inventory, net are as follows: September 30, 2017 December 31, 2017 Raw materials and supplies $ 64,113 $ 68,273 Work in progress 16,425 19,313 Finished goods and products held for resale 44,402 45,211 Costs of unbilled projects 5,706 6,378 Reserves for excess and obsolete (10,599 ) (10,869 ) $ 120,047 $ 128,306

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant, and Equipment Property, plant, and equipment consists of the following: September 30, 2017 December 31, 2017 Machinery and equipment $ 338,056 $ 345,820 Land and buildings 84,282 85,946 Construction in process 24,788 28,354 447,126 460,120 Less: accumulated depreciation (167,083 ) (178,613 ) $ 280,043 $ 281,507 Depreciation expense was $12,427 and $14,007 for the three months ended December 31, 2016 and 2017 , respectively. Maintenance and repair expense was $5,155 and $5,814 for the three months ended December 31, 2016 and 2017 , respectively.

Goodwill

Goodwill	3 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Changes in the carrying amount of goodwill are as follows: September 30, December 31, Balance at beginning of period $ 267,643 $ 321,913 Business combinations 52,404 0 Measurement period adjustment (301 ) 0 Foreign currency translation 2,167 (986 ) Balance at end of period $ 321,913 $ 320,927 As of September 30 and December 31, 2017 , $139,581 and $120,832 , respectively, of goodwill is deductible for tax purposes. The Neptune Benson reporting unit fair value excess was approximately 3.0% above the carrying value as of the date of valuation on July 1, 2017. The Company continues to monitor this reporting unit and noted no events that would cause a revaluation during the three months ending December 31, 2017 . All other reporting units significantly exceeded their carrying value and as such, no further analysis was performed.

Debt

Debt	3 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt Long‑term debt consists of the following: September 30, 2017 December 31, 2017 First Lien Term Facility, due December 20, 2024 $ 896,574 $ 794,583 Revolving Credit Facility, due January 15, 2019 — — Build Own Operate Financing, due June 30, 2024 6,930 6,677 Notes Payable, due June 30, 2018 to July 31, 2023 3,287 2,869 Total debt 906,791 804,129 Less unamortized discount and lender fees (16,942 ) (15,196 ) Total net debt 889,849 788,933 Less current portion (11,325 ) (11,033 ) Total long‑term debt $ 878,524 $ 777,900 Term Facilities and Revolving Credit Facility On January 15, 2014, EWT Holdings III Corp. (“EWT III”), an indirect wholly-owned subsidiary of the Company, entered into a First Lien Credit Agreement and Second Lien Credit Agreement (the “Credit Agreements”) among EWT III, EWT Holdings II Corp., the lenders party thereto and Credit Suisse AG as administrative agent and collateral agent. The First Lien Credit Agreement provided seven -year term loan facility, and the Second Lien Credit Agreement provided for an eight -year term loan facility. The term loan facilities originally consisted of the “First Lien Term Loan” and “Second Lien Term Loan” in aggregate principal amounts of $505,000 and $75,000 , respectively. The First Lien Credit Agreement also made available to the Company a $75,000 revolving credit facility (the "Revolver”), which provided for a letter of credit sub-facility up to $ 35,000 . During the year ending September 30, 2017 , certain subsidiaries of the Company entered into two amendments to the First Lien Credit Agreement, which provided for, among other things, the payoff and termination of the Second Lien Term Loan, the upsize of the First Lien Term Loan by $ 230,000 , excluding impact of quarterly repayments, and the upsize of the Revolver from $ 75,000 to $ 95,000 . On December 20, 2017, certain subsidiaries of the Company entered into Amendment No. 5 (the “Fifth Amendment”), among EWT III, as the borrower, certain other subsidiaries of the Company, and Credit Suisse AG, as administrative agent and collateral agent, relating to the First Lien Credit Agreement (as amended, amended and restated, extended, supplemented or otherwise modified from time to time prior to the effectiveness of the Fifth Amendment, the “Existing Credit Agreement”). Prior to the Fifth Amendment, approximately $ 796,574 was outstanding under the First Lien Term Loan (the “Existing Term Loans”). Pursuant to the Fifth Amendment, the Existing Term Loans were refinanced with the proceeds of refinancing term loans. The principal and interest under the First Lien Term Loan is payable in quarterly installments, with quarterly principal payments of $ 1,991 , and the balance is due at maturity on December 20, 2024. Total deferred fees related to the First Lien Term Loan were $16,942 and $15,196 , net of amortization, as of September 30 and December 31, 2017 , respectively. These fees were included as a contra liability to debt on the Consolidated balance sheets. Pursuant to the Fifth Amendment, the Existing Credit Agreement was amended to, among other things, (i) reduce the interest rate spread applicable to term loans based on LIBOR from (A) 3.75% to 2.75% during any period during which EWT III maintains a public corporate family rating better than or equal to B1 from Moody’s and B+ from S&P, in each case with a stable outlook (a “Ratings Condition Period”), and (B) 3.75% to 3.00% for any period other than a Ratings Condition Period; (ii) extend the maturity of term loans outstanding under the Existing First Lien Credit Agreement to December 20, 2024, from January 15, 2021; (iii) reduce the interest rate spread applicable to revolving credit loans of certain revolving credit lenders who agreed to the extension of maturity described below (the “Extending Revolving Lenders”) based on LIBOR from (A) 3.25% to 2.75% during any period during which the first lien net leverage ratio exceeds 2.5x, and (B) 3.00% to 2.50% during any period during which the first lien net leverage ratio is less than or equal to 2.5x; (iv) extend the maturity of the revolving credit loans of Extending Revolving Lenders outstanding under the Existing Credit Agreement to December 20, 2022, from January 15, 2019; (v) increase the revolving credit commitment to $125,000 from $95,000 ; (vi) extend the 1.00% prepayment penalty for refinancings in connection with certain repricing transactions through June 20, 2018; and (vii) increase the letter of credit sublimit to $45,000 from $35,000 . The Fifth Amendment bifurcated the Revolver, with $87,500 of the $125,000 revolver capacity maturing on December 20, 2022 (the “2022 Borrowings”), and the remaining $37,500 maturing on January 15, 2019 (the “2019 Borrowings”). Borrowings under the Revolver bear interest at variable rates plus a margin ranging from 200 to 325 basis points, and 150 to 275 basis points for 2019 and 2022 Borrowings, respectively, dependent upon the Company’s leverage ratio and variable rate selected. 2022 Base Rate borrowings under the Revolver would have incurred interest at 6.25% as of December 31, 2017 , calculated as the 175 basis point spread plus the prime rate of 4.50% . 2019 Base Rate borrowings under the Revolver at September 30 and December 31, 2017 would have incurred interest at 6.5% and 6.75% , respectively, calculated as the 225 basis point spread plus the Prime Rate of 4.25% at September 30, 2017 and 4.50% at December 31, 2017 . The Company had borrowing availability under the Revolver of $95,000 and $125,000 at September 30 and December 31, 2017 , respectively, reduced for outstanding letter of credit guarantees. Such letter of credit guarantees are subject to a $45,000 sublimit within the Revolver, increased from $35,000 as part of the Fifth Amendment. The Company’s outstanding letter of credit guarantees under this agreement aggregated approximately $6,706 and $6,534 , at September 30, and December 31, 2017 , respectively. The Company had no outstanding revolver borrowings as of September 30, and December 31, 2017 , and unused amounts, defined as total revolver capacity less outstanding letters of credit and revolver borrowings, of $88,294 and $118,466 , respectively. At September 30, and December 31, 2017 , the Company had additional letters of credit of $10,568 and $12,238 issued under a separate arrangement, respectively. The First Lien Credit Agreement contains limitations on incremental borrowings, is subject to leverage ratios and allows for optional prepayments. Under certain circumstances beginning with fiscal 2015 results of operations, the Company may be required to remit excess cash flows as defined based upon exceeding certain leverage ratios. The Company did not exceed such ratios during fiscal 2017, does not anticipate exceeding such ratios during 2018, and therefore does not anticipate any additional repayments during 2018. On June 30, 2017, the Company completed a Build Own Operate financing for $7,100 . The Company incurred $50 of additional financing fees related to this transaction, which have been capitalized and are included as a contra liability on the balance sheet. This financing fully amortizes over the seven -year tenure and incurs interest at a rate of one-month LIBOR plus 300 basis points. This variable rate debt has been fixed at a rate of 5.08% per annum. Principal obligations are $254 per quarter. The Company had $6,677 principal outstanding under this facility at December 31, 2017. Notes Payable As of September 30 and December 31, 2017 , the Company had notes payable in an aggregate outstanding amount of $3,287 and $2,869 , with interest rates ranging from 6.26% to 7.39% , and due dates ranging from June 30, 2018 to July 31, 2023. These notes are related to certain equipment related contracts and are secured by the underlying equipment and assignment of the related contracts. Repayment Schedule Aggregate maturities of all long‑term debt, including current portion of long‑term debt and excluding capital lease obligations as of September 30, 2017 , are presented below: Fiscal Year Remainder of 2018 $ 7,499 2019 9,503 2020 9,402 2021 9,429 2022 9,459 Thereafter 758,837 Total $ 804,129

Product Warranties

Product Warranties	3 Months Ended
	Dec. 31, 2017
Guarantees and Product Warranties [Abstract]
Product warranties	Product Warranties The Company accrues warranty obligations associated with certain products as revenue is recognized. Provisions for the warranty obligations are based upon historical experience of costs incurred for such obligations, adjusted for site‑specific risk factors and as necessary, for current conditions and factors. There are significant uncertainties and judgments involved in estimating warranty obligations, including changing product designs, differences in customer installation processes and future claims experience which may vary from historical claims experience. A reconciliation of the activity related to the accrued warranty, including both the current and long‑term portions, is as follows: Three Months Ended December 31, 2016 2017 Balance at beginning of the period $ 23,309 $ 17,274 Warranty provision for sales 1,085 1,522 Settlement of warranty claims (2,889) (2,563) Foreign currency and other (522) 71 Balance at end of the period $ 20,983 $ 16,304 The decline in accrued warranty over the periods presented is attributable to improved product quality and better project execution, as well as the expiration of warranty periods for certain specific exposures related to discontinued products.

Restructuring and Related Charg

Restructuring and Related Charges	3 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and related charges	Restructuring and Related Charges To better align its resources with its growth strategies and reduce the cost structure, the Company commits to restructuring plans as necessary. The Company initiated a Voluntary Separation Plan (VSP) during the year ended September 30, 2016 , that continued throughout fiscal years 2017 and 2018 . The VSP plan includes severance payments to employees as a result of streamlining business operations for efficiency, elimination of redundancies, and reorganizing business processes. In addition, the Company has undertaken various other restructuring initiatives, including the wind down of the Company’s operations in Italy, restructuring of the Company’s operations in Australia, consolidation of functional support structures on a global basis, and consolidation of the Singaporean research and development center. The table below sets forth the amounts accrued for the restructuring components and related activity: Three Months Ended December 31, 2016 2017 Balance at beginning of the period $ 13,217 $ 3,542 Restructuring charges related to VSP 10,189 382 Charges related to other initiatives 1,283 3,744 Write off charge and other non‑cash activity (913) (244) Cash payments (10,178) (5,498) Other adjustments (92) 1 Balance at end of the period $ 13,506 $ 1,927 The balances for accrued restructuring liabilities at September 30, and December 31, 2017 , are recorded in Accrued expenses and other liabilities. Restructuring charges primarily represent severance charges. The Company expects to pay out the remaining amounts accrued as of September 30, 2017 during the quarter March 31, 2018. The Company continues to evaluate restructuring activities that may result in additional charges in the future.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee benefit plans	Employee Benefit Plans The Company maintains multiple employee benefit plans. Certain of the Company’s employees in the UK were participants in a Siemen’s defined benefit plan established for employees of a UK-based operation acquired by Siemens in 2004. The plan was frozen with respect to future service credits for active employees, however the benefit formula recognized future compensation increases. The Company agreed to establish a replacement defined benefit plan, with the assets of the Siemens scheme transferring to the new scheme on April 1, 2015. The Company’s employees in Germany also participate in a defined benefit plan. Assets equaling the plan’s accumulated benefit obligation were transferred to a German defined benefit plan sponsored by the Company upon the acquisition of EWT from Siemens. The German entity also sponsors a defined benefit plan for a small group of employees located in France. Pension expense for the German and UK plans were as follows: Three Months Ended December 31, 2016 2017 Service cost $ 251 $ 233 Interest cost 77 118 Expected return on plan assets (38) (31) Amortization of actuarial losses 176 76 Pension expense for defined benefit plans $ 466 $ 396

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax provision for interim periods is comprised of tax on ordinary income (loss) provided at the most recent estimated annual effective tax rate, adjusted for the tax effect of discrete items. Management estimates the annual effective tax rate quarterly based on the forecasted pretax income (loss) results of its U.S. and non-US jurisdictions. Items unrelated to current year ordinary income (loss) are recognized entirely in the period identified as a discrete item of tax. These discrete items generally relate to changes in tax laws, adjustments to the actual liability determined upon filing tax returns, and adjustments to previously recorded reserves for uncertain tax positions. Effects of the Tax Cuts and Jobs Act New tax legislation, commonly referred to as the Tax Cuts and Jobs Act, was enacted on December 22, 2017. ASC 740, Accounting for Income Taxes , requires companies to recognize the effect of tax law changes in the period of enactment even though the effective date for most provisions is for tax years beginning after December 31, 2017, or in the case of certain other provisions, January 1, 2018. Though certain key aspects of the new law are effective January 1, 2018 and have an immediate accounting effect, other significant provisions are not effective or may not result in accounting effects for September 30 fiscal year companies until October 1, 2018. The SEC issued Staff Accounting Bulletin No. 118 (SAB 118), which allows registrants to record provisional amounts during a one year “measurement period” similar to that used when accounting for business combinations. During the measurement period, impacts of the law are expected to be recorded at the time a reasonable estimate for all or a portion of the effects can be made, and provisional amounts can be recognized and adjusted as information becomes available, prepared or analyzed. The SAB summarizes a three-step process to be applied at each reporting period to account for and qualitatively disclose: (1) the effects of the change in tax law for which accounting is complete; (2) provisional amounts (or adjustments to provisional amounts) for the effects of the tax law where accounting is not complete, but that a reasonable estimate has been determined; and (3) a reasonable estimate cannot yet be made and therefore taxes are reflected in accordance with law prior to the enactment of the Tax Cuts and Jobs Act. Amounts recorded where accounting is complete in the three months ended December 31, 2017 principally relate to the reduction in the U.S. corporate income tax rate to 21% , which resulted in the Company reporting an income tax benefit of $3,500 to remeasure deferred taxes liabilities associated with indefinitely lived intangible assets that will reverse at the new 21% rate. Absent this deferred tax liability, the Company is in a net deferred tax asset position that is offset by a full valuation allowance. Though the impact of the rate change has a net tax effect of zero, the accounting to determine the gross change in the deferred tax position and the offsetting valuation is not yet complete. The new law includes a one-time mandatory repatriation transition tax on the net accumulated earnings and profits of a U.S. taxpayer’s foreign subsidiaries. The Company has performed a preliminary analysis, and as a result of an expected overall foreign deficit since inception in early 2014, it is not likely that the Company will be subject to the transition tax. Therefore, the accounting for this matter is provisional until the accumulated earnings and profits analysis is finalized in fiscal 2018. Effects of tax law changes where a reasonable estimate of the accounting effects has not yet been made include additional limitations on certain meals and entertainment expenses, the inclusion of commissions and performance based compensation in determining the excessive compensation limitation, and the unlimited carryforward of net operating losses. Other significant provisions that are not yet effective but may impact income taxes in future years include: an exemption from U.S. tax on dividends of future foreign earnings, limitation on the current deductibility of net interest expense in excess of 30% of adjusted taxable income, a limitation of net operating losses generated after fiscal 2018 to 80% of taxable income, new rules for the taxable year of when to recognize income, an incremental tax (base erosion anti-abuse tax or BEAT) on excessive amounts paid to foreign related parties, and a minimum tax on certain foreign earnings in excess of 10% of the foreign subsidiaries tangible assets (i.e., global intangible low-taxed income of GILTI). The company is still evaluating whether to make a policy election to treat the GILTI tax as a period expense or to provide U.S. deferred taxes on foreign temporary differences that are expected to generate GILTI income when they reverse in future years. Annual Effective Tax Rate The full year estimated annual effective tax rate, which excludes the impact of discrete items, was 34.9% and 15.6% as of the three months ended December 31, 2016 and 2017 and is reconciled to the U.S. statutory rate as follows. For the three months ended December 31, 2016, the annual effective tax rate of 34.9% approximates the U.S. federal statutory rate; however the mix of U.S. and non U.S. income, and the statutory tax rates at which each is taxed, decreased the annual effective tax rate by 8.1% . The release of valuation allowances as a result of forecasted earnings also decreased the annual effective tax rate by 2.0% . These decreases were offset principally due to permanently disallowed interest in certain foreign jurisdictions, nondeductible meals and entertainment and other amounts that were not material individually and in the aggregate. For the three months ended December 31, 2017, the U.S. federal statutory rate of 24.5% is a blended rate based upon the number of days in fiscal 2018 that the company will be taxed at the former statutory rate of 35% and the number of days that it will be taxed at the new rate of 21% . The annual effective tax rate of 15.6% differs from this blended U.S. federal statutory rate principally due to higher forecasted U.S. earnings that permitted the realization of net deferred tax assets which were previously impaired with a valuation allowance. The reduction in the U.S. statutory rate has significantly lessened the impact of foreign statutory tax rate differences to 0.2% on the annual effective tax rate as a majority of the Company’s foreign income is in jurisdictions with a similar or slightly higher tax rate than 24.5% . Prior and Current Period Tax Expense For the three months ended December 31, 2016, income tax benefits of $7,095 as a percentage of pretax losses of $20,295 were 35.0% . This approximates the estimated annual effective tax rate of 34.9% as discrete items were not material. For the three months ended December 31, 2017, income tax benefits of $4,410 as a percentage of pretax losses of $7,415 were 59.5% . This is higher than the estimated annual effective tax rate of 15.6% primarily due to recording a discrete period tax benefit of $3,500 for the remeasurement of U.S. deferred taxes liabilities associated with indefinite lived intangible assets for the reduction in the U.S. statutory rate from 35% to 21% . Other discrete items were not material. The Company projects to maintain a full valuation on U.S. federal and state net deferred tax assets (excluding the tax effects of deferred tax liabilities associated with indefinite lived intangibles) for the year ended September 30, 2018 as a result of pretax losses incurred since the Company’s inception in early 2014. Though the Company reported positive earnings for the first time in 2017 and is projecting earnings in 2018, Management believes it is prudent to retain a valuation allowance until a more consistent pattern of actual earnings is established and net operating loss carryforwards begin to be utilized. There are no amounts of unrecognized tax benefits recorded for the three months ended December 31, 2016 or 2017. Management does not reasonably expect any significant changes to unrecognized tax benefits within next twelve months of the reporting date. U.S. federal, state and foreign tax returns remain open to examination for the year ended September 30, 2014 and forward

Share Based Compensation

Share Based Compensation	3 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Based Compensation	Share-based compensation expense was $466 and $2,612 during the three months ended December 31, 2016 and 2017, respectively. The unrecognized compensation expense related to stock options and restricted stock units was $3,454 and $22,917 , respectively at December 31, 2017, and is expected to be recognized over a weighted average period of 3.7 years and 1.8 years, respectively. Option awards vest rateably at 25% per year, and are exercisable at the time of vesting. The options granted have a ten -year contractual term. A summary of the stock option activity as of December 31, 2017 is presented below (amounts in thousands except per share amounts): Options Weighted Average Exercise Price/Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2017 9,060 $ 5.18 7.5 years $ 11,011 Granted — — Exercised — — Forfeited (11 ) 4.86 (10 ) Expired — — Outstanding at December 31, 2017 9,049 5.18 7.3 years $ 11,001 Options exercisable at December 31, 2017 5,306 $ 4.80 9.9 years $ 5,433 A summary of the status of the Company's non-vested stock options as of and for the three month period ended December 31, 2017 is presented below. Shares Weighted Average Grant Date Fair Value/Share Nonvested at September 30, 2017 4,335 $ 1.36 Granted — Vested (685 ) 0.97 Forfeited (11 ) 0.87 Nonvested at December 31, 2017 3,639 $ 1.44 The total fair value of options vested during the three months ended December 31, 2017, was $663 . In connection with our IPO, the Board adopted and our stockholders approved the Evoqua Water Technologies Corp. 2017 Equity Incentive Plan (or the "Equity Incentive Plan"), under which equity awards may be made in the respect of 5,100 shares of common stock of the Company. Under the Equity Incentive Plan, awards may be granted in the form of options, restricted stock, restricted stock units, stock appreciation rights, dividend equivalent rights, share awards and performance-based awards (including performance share units and performance-based restricted stock). No awards have been granted as of December 31, 2017 under the Equity Incentive Plan. Restricted Stock Units In connection with our IPO, the Company entered into restricted stock unit (“RSU”) agreements with each of our executive officers and certain other key members of management pursuant to which recipients received, in the aggregate 1,197 stock-settled RSUs, the aggregate value of which equals $25,000 . The RSUs will vest and settle in full upon the second anniversary of the IPO (the “Vesting Date”). The following is a summary of the RSU activity for the three months ended December 31, 2017. Shares Weighted Average Grant Date Fair Value/Share Outstanding at September 30, 2017 — $ — Granted 1,197 20.88 Outstanding at December 31, 2017 1,197 $ 20.88

Concentration of Credit Risk

Concentration of Credit Risk	3 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Concentration of credit risk	Concentration of Credit Risk The Company’s cash and cash equivalents and accounts receivable are potentially subject to concentration of credit risk. Cash and cash equivalents are placed with financial institutions that management believes are of high credit quality. Accounts receivable are derived from revenue earned from customers located in the U.S. and internationally and generally do not require collateral. The Company’s trade receivables do not represent a significant concentration of credit risk at fiscal 2016 and 2017 due to the wide variety of customers and markets into which products are sold and their dispersion across geographic areas. The Company does perform ongoing credit evaluations of its customers and maintains an allowance for potential credit losses on trade receivables. As of and for the fiscal three months ended December 31, 2016 and 2017 no customer accounted for more than 10% of net sales or net accounts receivable. The Company operates predominantly in seven countries worldwide and provides a wide range of proven product brands and advanced water and wastewater treatment technologies, mobile and emergency water supply solutions and service contract options through its Industrial, Municipal, and Products segments. The Company is a multi-national business but its sales and operations are primarily in the U.S. Sales to unaffiliated customers are based on the Company locations that maintain the customer relationship and transacts the external sale.

Related_Party Transactions

Related‑Party Transactions	3 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related-party transactions	Related‑Party Transactions Transactions with Investors The Company paid an advisory fee of $1,000 per quarter to AEA Investors LP (“AEA”), the private equity firm and ultimate majority shareholder. Upon the IPO, the Company stopped paying these fees to AEA and as a result, only paid $333 during the three months ended December 31, 2017 . In addition, the Company reimbursed AEA for normal and customary expenses incurred by AEA on behalf of the Company. The Company incurred expenses, excluding advisory fees, of $57 and $33 for the three months ended December 31, 2016 and 2017 , respectively. The amounts owed to AEA were $38 and $0 at December 31, 2017 , and September 30, 2017 , respectively, and were included in Accrued expenses and other liabilities. AEA, through two of its affiliated funds, is one of the lenders in the Incremental First Lien Facility and had a commitment of $16,218 and $14,409 at September 30, 2017 and December 31, 2017 , respectively. The Company also has a related party relationship with one of their customers, who is also a shareholder of the Company. The Company had sales to this customer of $175 and $296 , respectively, as of December 31, 2016 and 2017 and was owed $2,354 and $1,063 from them at September 30 and December 31, 2017 , respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company occupies certain facilities and operates certain equipment and vehicles under non‑cancelable lease arrangements. Lease agreements may contain lease escalation clauses and purchase and renewal options. The Company recognizes scheduled lease escalation clauses over the course of the applicable lease term on a straight-line basis in the Consolidated Statement of Operations. Total rent expense was $2,772 and $3,113 for the three months ended December 31, 2016 and 2017 respectively. Future minimum aggregate rental payments under non-cancelable operating leases are as follows: Operating Fiscal Year Remainder of 2018 $ 8,362 2019 9,766 2020 8,317 2021 6,362 2022 4,037 Thereafter 10,236 Total $ 47,080 Capital Leases The gross and net carrying values of the equipment under capital leases was $43,727 and $30,302 , respectively, as of September 30, 2017 and was $46,063 and $30,531 , respectively, as of December 31, 2017 and are recorded in Property, plant and equipment, net. The following is a schedule showing the future minimum lease payments under capital leases by years and the present value of the minimum lease payments as of December 31, 2017 . Capital Fiscal Year Remainder of 2018 $ 7,962 2019 9,635 2020 7,596 2021 4,738 2022 2,976 Thereafter 1,573 Total 34,480 Less amount representing interest (at rates ranging from 2.15% to 3.65%) 3,359 Present value of net minimum capital lease payments 31,121 Less current installments of obligations under capital leases 10,304 Obligations under capital leases, excluding current installments $ 20,817 The current installments of obligations under capital leases are included in Accrued expenses and other liabilities. Obligations under capital leases, excluding current installments, are included in other non-current liabilities. The Company is a lessor to multiple parties. The Company purchases equipment through internal funding or bank debt equal to the fair market value of the equipment. The equipment is then leased to customers for periods ranging from five to twenty years . As of December 31, 2017 , future minimum lease payments receivable under operating leases are as follows: Operating Fiscal year Remainder of 2018 $ 4,922 2019 4,608 2020 3,821 2021 1,786 2022 1,796 Thereafter 3,687 Future minimum lease payments $ 20,620 Guarantees From time to time, the Company is required to provide letters of credit, bank guarantees, or surety bonds in support of its commitments and as part of the terms and conditions on water treatment projects. In addition, the Company is required to provide letters of credit or surety bonds to the department of environmental protection or equivalent in some states in order to maintain its licenses to handle toxic substances at certain of its water treatment facilities. These financial instruments typically expire after all Company commitments have been met, a period typically ranging from twelve months to ten years , or more in some circumstances. The letters of credit, bank guarantees, or surety bonds are arranged through major banks or insurance companies. In the case of surety bonds, the Company generally indemnifies the issuer for all costs incurred if a claim is made against the bond. As of September 30 and December 31, 2017 and the Company had letters of credit totaling $18,772 , and $17,274 , respectively, and surety bonds totaling $90,985 and $87,849 respectively, outstanding under the Company’s credit arrangements. The longest maturity date of the letters of credit and surety bonds in effect as of December 31, 2017 was March 31, 2024. Additionally, as of September 30 and December 31, 2017 , the Company had letters of credit totaling $909 and $901 , respectively, and surety bonds totaling $12,967 and $12,970 , respectively, outstanding under the Company’s prior arrangement with Siemens. Litigatiop From time to time, as a normal incident of the nature and kind of business in which the Company is engaged, various claims or charges are asserted and litigation commenced against it arising from or related to: product liability; personal injury; trademarks, trade secrets or other intellectual property; labor and employee disputes; commercial or contractual disputes; breach of warranty; or environmental matters. Claimed amounts may be substantial but may not bear any reasonable relationship to the merits of the claim or the extent of any real risk of court or arbitral awards. While it is not feasible to predict the outcome of these matters with certainty, and some lawsuits, claims or proceedings may be disposed or decided unfavorably, the Company does not expect that any asserted or un-asserted legal claims or proceedings, individually or in the aggregate, will have a material adverse effect on the results of operations, or financial condition.

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	3 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following: September 30, 2017 December 31, 2017 Salaries, wages and other benefits $ 52,116 $ 27,051 Severance payments 3,542 1,927 Taxes, other than income 9,244 10,039 Obligation under capital leases 9,777 10,304 Third party commissions 6,968 5,945 Insurance liabilities 4,915 6,092 Provisions for litigation 4,715 1,056 Earn outs related to acquisitions 4,304 4,304 Other 26,342 22,075 $ 121,923 $ 88,793 The reduction in Accrued Expenses and Other Liabilities is primarily due to timing of cash payments for various employee-related liabilities, along with the payment of accrued expenses related to the strategic transaction during the three months ended December 31, 2017.

Business Segments

Business Segments	3 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Business segments	Business Segments The Company has three reportable segments – Industrial, Municipal and Products. The key factors used to identify these reportable segments are the organization and alignment of the Company’s internal operations, the nature of the products and services, and customer type. The business segments are described as follows: Industrial combines equipment and services to improve operational reliability and environmental compliance for heavy and light industry, commercial and institutional markets. Their customers span industries including hydrocarbon refineries, chemical processing, power, food and beverage, life sciences, health services and microelectronics. Municipal helps engineers and municipalities meet new demands for plant performance through leading equipment, solutions and services backed by trusted brands and over 100 plus years of applications experience. Their customers include waste water and drinking water collection and distribution systems, utility operators. Their services include odor control services. Products has distinct business operating units. Each has a unique standard product built on well-known brands and technologies that are sold globally through multiple sales and aftermarket channels. Additionally, Products also offers industrial, municipal and water recreational users with well-known brands that improve operational reliability and environmental compliance. Their customers include original equipment manufacturers, regional and global distributors, engineering, procurement and contracting customers, and end users in the municipal, industrial and commercial industries, including hotels, resorts, colleges, universities, waterparks, aquariums and zoos. The Company evaluates its business segments’ operating results based on earnings before interest, taxes, depreciation and amortization. Corporate activities include general corporate expenses, elimination of intersegment transactions, interest income and expense and other unallocated charges. Unallocated charges include certain restructuring and other business transformation charges that have been undertaken to align and reposition the Company to the current reporting structure, acquisition related costs (including transaction costs, certain integration costs and recognition of backlog intangible assets recorded in purchase accounting) and stock-based compensation charges. Since certain administrative and other operating expenses and other items have not been allocated to business segments, the results in the below table are not necessarily a measure computed in accordance with generally accepted accounting principles and may not be comparable to other companies. Three Months Ended December 31, 2016 2017 Total sales Industrial $ 147,005 $ 168,269 Municipal 69,385 69,313 Products 78,967 81,552 Total sales 295,357 319,134 Intersegment sales Industrial 1,299 3,075 Municipal 6,754 7,407 Products 7,432 11,601 Total intersegment sales 15,485 22,083 Sales to external customers Industrial 145,706 165,194 Municipal 62,631 61,906 Products 71,535 69,951 Total sales 279,872 297,051 Earnings before interest, taxes, depreciation and amortization (EBITDA) Industrial 32,001 40,127 Municipal 8,562 6,592 Products 14,918 10,699 Corporate (42,376 ) (27,707 ) Total EBITDA 13,105 29,711 Depreciation and amortization Industrial 8,912 10,145 Municipal 2,076 1,799 Products 3,522 2,985 Corporate 4,137 4,954 Total depreciation and amortization 18,647 19,883 (Loss) income from operations Industrial 23,089 29,982 Municipal 6,486 4,793 Products 11,396 7,714 Corporate (46,513 ) (32,661 ) Total (loss) income from operations (5,542 ) 9,828 Interest expense (14,753 ) (17,243 ) Loss before income taxes (20,295 ) (7,415 ) Income tax benefit 7,095 4,410 Net loss $ (13,200 ) $ (3,005 ) Capital expenditures Industrial $ 10,998 $ 8,948 Products 985 1,182 Municipal 596 1,747 Corporate 1,024 3,380 Total Capital expenditures $ 13,603 $ 15,257 September 30, December 31, Assets Industrial $ 461,471 $ 470,035 Municipal 155,698 147,925 Products 513,941 518,759 Corporate 342,199 342,190 Total assets $ 1,473,309 $ 1,478,909 Goodwill Industrial $ 128,190 $ 127,132 Municipal 9,865 9,880 Products 183,858 183,915 Total goodwill $ 321,913 $ 320,927

Earnings per share

Earnings per share	3 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings per share	Earnings Per Share The following table sets forth the computation of basic and diluted loss from continuing operations per common share (in thousands, except per share amounts): Three Months Ended December 31, 2016 2017 Numerator: Numerator for basic and diluted loss per common share—Net (loss) income attributable to Evoqua Water Technologies $ (13,599 ) $ (3,713 ) Denominator: Denominator for basic net (loss) income per common share—weighted average shares 104,782 109,974 Effect of dilutive securities: Share‑based compensation — — Denominator for diluted net loss per common share—adjusted weighted average shares 104,782 109,974 Basic (loss) income attributable to Evoqua Water Technologies per common share $ (0.13 ) $ (0.03 ) Diluted (loss) income attributable to Evoqua Water Technologies per common share $ (0.13 ) $ (0.03 ) Since the Company was in a net loss position for the three months ended December 31, 2016 and 2017 , there was no difference between the number of shares used to calculate basic and diluted loss per share. Because of their anti-dilutive effect, 9,012 and 10,246 common share equivalents comprised of employee stock options, have been excluded from the diluted EPS calculation for the three months ended December 31, 2016 and 2017 .

Subsequent Events (Notes)

Subsequent Events (Notes)	3 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company announced on February 1, 2018 the acquisition of Pure Water Solutions, a leading provider of high-purity water equipment and systems, service deionization and resin regeneration, with service operations in suburban Denver, CO and Santa Fe, NM for $4,699 ; $3,706 cash paid upon closing with another $993 earn out payments to be paid out twelve months after the closing. Pure Water Solutions will become part of a part of the Industrial Segment, and will extend the Company’s unmatched service network.

Description of the Company an30

Description of the Company and Basis of Presentation - (Policies)	3 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of Presentation The accompanying Unaudited Condensed Consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP). All intracompany transactions have been eliminated. The unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such SEC rules. We believe that the disclosures made are adequate to make the information presented not misleading. We consistently applied the accounting policies described in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017 , as filed with the SEC on December 4, 2017 (“ 2017 Annual Report”), in preparing these unaudited condensed consolidated financial statements, with the exception of accounting standard updates described in Note 2. These condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes included in our 2017 Annual Report.
Fiscal Year	Fiscal Year The Company’s fiscal year ends on September 30.
Use of estimates	Use of Estimates The unaudited condensed consolidated financial statements have been prepared in conformity with U.S. GAAP and require management to make estimates and assumptions. These assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Estimates and assumptions are used for, but not limited to: (i) revenue recognition; (ii) allowance for doubtful accounts; (iii) inventory valuation, asset valuations, impairment, and recoverability assessments; (iv) depreciable lives of assets; (v) useful lives of intangible assets; (vi) income tax reserves and valuation allowances; and (vii) product warranty and litigation reserves. Estimates are revised as additional information becomes available. Actual results could differ from these estimates.
Cash and cash equivalents	Cash and Cash Equivalents Cash and cash equivalents are liquid investments with an original maturity of three or fewer months when purchased.
Accounts receivable	Accounts Receivable Receivables are primarily comprised of uncollected amounts owed to us from transactions with customers and are presented net of allowances for doubtful accounts. Allowances are estimated based on historical write‑offs and the economic status of customers. The Company considers a receivable delinquent if it is unpaid after the term of the related invoice has expired. Write‑offs are recorded at the time all collection efforts have been exhausted.
Inventories	Inventories Inventories are stated at the lower of cost or market, where cost is generally determined on the basis of an average or first‑in, first‑out (FIFO) method. Production costs comprise direct material and labor and applicable manufacturing overheads, including depreciation charges. The Company regularly reviews inventory quantities on hand and writes off excess or obsolete inventory based on estimated forecasts of product demand and production requirements. Manufacturing operations recognize cost of product sales using standard costing rates with overhead absorption which generally approximates actual cost.
Property, plant and equipment	Property, Plant, and Equipment Property, plant, and equipment is valued at cost less accumulated depreciation and impairment losses. If the costs of certain components of an item of property, plant, and equipment are significant in relation to the total cost of the item, they are accounted for and depreciated separately. Depreciation expense is recognized using the straight‑line method. Useful lives are reviewed annually and, if expectations differ from previous estimates, adjusted accordingly. Estimated useful lives for major classes of depreciable assets are as follows: Asset Class Estimated Useful Life Machinery and equipment 3 to 20 years Buildings and improvements 10 to 40 years Leasehold improvements are depreciated over the shorter of their estimated useful life or the term of the lease. Costs related to maintenance and repairs that do not extend the assets’ useful life are expensed as incurred.
Goodwill and other intangible assets	Goodwill and Other Intangible Assets Goodwill represents purchase consideration paid in a business combination that exceeds the value assigned to the net assets of acquired businesses. Other intangible assets consist of customer‑related intangibles, proprietary technology, software, trademarks and other intangible assets. The Company amortizes intangible assets with definite useful lives on a straight‑line basis over their respective estimated economic lives which range from 1 to 26 years. The Company reviews goodwill to determine potential impairment annually during the fourth quarter of our fiscal year, or more frequently if events and circumstances indicate that the asset might be impaired. Impairment testing for goodwill is performed at a reporting unit level. We have determined that we have four reporting units. Our quantitative impairment testing utilizes both a market (guideline public company) and income (discounted cash flows) method for determining fair value. In estimating the fair value of the reporting unit utilizing a discounted cash flow (“DCF”) valuation technique, we incorporate our judgment and estimates of future cash flows, future revenue and gross profit growth rates, terminal value amount, capital expenditures and applicable weighted‑average cost of capital used to discount these estimated cash flows. The estimates and projections used in the estimate of fair value are consistent with our current budget and long‑range plans, including anticipated change in market conditions, industry trend, growth rates and planned capital expenditures, among other considerations.
Impairment of long-lived assets	Impairment of Long‑Lived Assets Long‑lived assets, such as property, plant, and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. Recoverability of the asset or asset group is measured by comparison of its carrying amount to undiscounted future net cash flows the asset or asset group is expected to generate. If the carrying amount of an asset or asset group is not recoverable, the Company recognizes an impairment loss based on the excess of the carrying amount of the asset or asset group over its respective fair value which is generally determined as the present value of estimated future cash flows or as the appraised value.
Debt Issuance Costs And Debt Discounts	Debt Issuance Costs and Debt Discounts Debt issuance costs are capitalized and amortized over the contractual term of the underlying debt using the straight line method which approximates the effective interest method. Debt discounts and lender arrangement fees deducted from the proceeds have been included as a component of the carrying value of debt and are being amortized to interest expense using the effective interest method.
Revenue Recognition	Revenue Recognition Sales of goods and services are recognized when persuasive evidence of an arrangement exists, the price is fixed or determinable, collectability is reasonably assured and delivery has occurred or services have been rendered. For sales of aftermarket parts or products with a low level of customization and engineering time, the Company recognizes revenues at the time title and risks and rewards of ownership pass, which is generally when products are shipped or delivered to the customer as the Company has no obligation for installation. Sales of short‑term service arrangements are recognized as the services are performed, and sales of long‑term service arrangements are typically recognized on a straight‑line basis over the life of the agreement. For certain arrangements where there is significant customization to the product, the Company recognizes revenue under the provisions of Accounting Standards Codification (ASC) 605-35, Revenue Recognition – Construction-Type and Production-Type Contracts. These products include large capital water treatment projects, systems and solutions for municipal and industrial applications. Revenues from construction-type contracts are generally recognized under the percentage-of-completion method, based on the input of costs incurred to date as a percentage of total estimated contract costs. The nature of the contracts is generally fixed price with milestone billings. Approximately $47,063 and $59,387 of revenues from construction-type contracts were recognized on the percentage-of-completion method during the three months ended December 31, 2016 and 2017 , respectively. Contract revenues and cost estimates are reviewed and revised quarterly at a minimum and the cumulative effect of such adjustments are recognized in current operations. The amount of such adjustments have not been material. Cost and earnings in excess of billings under construction‑type arrangements are recorded when contracts have net asset balances where contract costs plus recognized profits less recognized losses exceed progress billings. Billings in excess of costs incurred are recorded when contract progress billings exceed costs and recognized profit less recognized losses. Approximately $8,792 and $6,383 of revenues from construction-type contracts were recognized on a completed contract method, which is typically when the product is delivered and accepted by the customer, during the three months ended December 31, 2016 and 2017 , respectively. The completed contract method is principally used when the contract is short in duration (generally less than twelve months) and where results of operations would not vary materially from those resulting from the use of the percentage-of-completion method.
Product warranties	Product Warranties Accruals for estimated expenses related to warranties are made at the time products are sold and are recorded as a component of Cost of product sales in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss. The estimated warranty obligation is based on product warranty terms offered to customers, ongoing product failure rates, material usage and service delivery costs expected to be incurred in correcting a product failure, as well as specific obligations for known failures and other currently available evidence. The Company assesses the adequacy of the recorded warranty liabilities on a regular basis and adjusts amounts as necessary.
Shipping and handling cost	Shipping and Handling Cost Shipping and handling costs are included as a component of cost of sales
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are provided against deferred tax assets when it is deemed more likely than not that some portion or all of the deferred tax asset will not be realized within a reasonable time period. We assess tax positions using a two‑step process. A tax position is recognized if it meets a more‑likely‑than‑not threshold, and is measured at the largest amount of benefit that is greater than 50.0% percent of being realized. Uncertain tax positions are reviewed each balance sheet date.
Sales Taxes	Sales Taxes Upon collection of sales tax from revenue, the amount of sales tax is placed into an accrued liability account. This liability is then relieved when the payment is sent to the proper government jurisdiction.
Foreign currency translations and transactions	Foreign Currency Translation and Transactions The functional currency for the international subsidiaries is the local currency. Assets and liabilities are translated into U.S. Dollars using current rates of exchange, while revenues and expenses are translated at the weighted‑average exchange rate for the period. The resulting translation adjustments are recorded in other comprehensive income/loss within shareholders equity.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred.
Equity-based compensation	Equity‑based Compensation The Company measures the cost of awards of equity instruments to employees based on the grant‑date fair value of the award. Prior to our IPO, given the absence of a public trading market for our common stock, the fair value of the common stock underlying our share‑based awards was determined by our board, with input from management, in each case using the income and market valuation approach. Stock options are granted with exercise prices equal to or greater than the estimated fair market value on the date of grant as authorized by our compensation committee. The grant‑date fair value is determined using the Black‑Scholes model. The fair value, net of estimated forfeitures, is amortized as compensation cost on a straight‑line basis over the vesting period primarily as a component of General and administrative expenses.
Earnings per share	Earnings per Share Basic earnings per common share is computed based on the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed based on the weighted average number of shares of common stock, plus the effect of diluted potential common shares outstanding during the period using the treasury stock method. Diluted potential common shares include outstanding stock options.
Retirement benefits	Retirement Benefits The Company applies, ASC Topic 715, Compensation—Retirement Benefits , which requires the recognition in pension obligations and accumulated other comprehensive income of actuarial gains or losses, prior service costs or credits and transition assets or obligations that have previously been deferred. The determination of retirement benefit pension obligations and associated costs requires the use of actuarial computations to estimate participant plan benefits to which the employees will be entitled. The significant assumptions primarily relate to discount rates, expected long‑term rates of return on plan assets, rate of future compensation increases, mortality, years of service, and other factors. The Company develops each assumption using relevant experience in conjunction with market‑related data for each individual country in which such plans exist. All actuarial assumptions are reviewed annually with third‑party consultants and adjusted as necessary. For the recognition of net periodic postretirement cost, the calculation of the expected return on plan assets is generally derived by applying the expected long‑term rate of return on the market‑related value of plan assets. The fair value of plan assets is determined based on actual market prices or estimated fair value at the measurement date.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Not Yet Adopted In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) . ASU No. 2014-09 clarifies the principles for recognizing revenue when an entity either enters into a contract with customers to transfer goods or services or enters into a contract for the transfer of non-financial assets. ASU 2014-09 may be adopted using either of two acceptable methods: (1) retrospective adoption to each prior period presented with the option to elect certain practical expedients; or (2) adoption with the cumulative effect recognized at the date of initial application and providing certain disclosures. To assess at which time revenue should be recognized, an entity should use the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The standard is effective for the Company for the quarter ending December 31, 2018. The Company has completed their first phase of adopting this standard, which was to identify the potential differences that will result from applying the new revenue recognition standard to the Company's contracts with its customers, and has begun the second step of reviewing their contracts to determine the impact of adopting the standard. At this time, the Company is not yet able to estimate the anticipated impact to the Condensed Consolidated financial statements. The Company is also evaluating the new disclosures required by the standard to determine what additional information will need to be disclosed. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . ASU No. 2016-02 requires recognition of operating leases as lease assets and liabilities on the balance sheet, and disclosure of key information about leasing arrangements. ASU No. 2016-02 will be effective retrospectively for the Company for the quarter ending December 31, 2019, with early adoption permitted. The Company is currently assessing the impact adoption of this guidance will have on the Company's Consolidated financial statements. In August 2016, the FASB issued ASU 2016‑15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) . This new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU No. 2016‑15 will be effective for the Company for the quarter ending December 31, 2018, with early adoption permitted. The guidance should be applied retrospectively to all periods presented, unless deem impracticable, in which case prospective application is permitted. The Company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. In October 2016, the FASB issued ASU 2016-17 , Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . The purpose of this update is to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The ASU requires the tax effects of all intra-entity sales of assets other than inventory to be recognized in the period in which the transaction occurs. The guidance will be effective for the Company for the quarter ending December 31, 2018 with early adoption permitted but only in the first interim period of a fiscal year. The changes are required to be applied by means of a cumulative-effect adjustment recorded in retained earnings as of the beginning of the fiscal year of adoption. The Company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. In February 2017, the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires the disaggregation of the service cost component from other components of net periodic benefit cost, clarifies how to present the service cost component and other components of net benefit costs in the Statements of Consolidated Operations and allows only the service cost component of net benefit costs to be eligible for capitalization. This ASU is effective for the Company for the quarter ending December 31, 2018. Adoption will be applied on a retrospective basis for the presentation of all components of net periodic benefit costs and on a prospective basis for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The company is currently evaluating the impact this guidance will have on the Consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU 2017‑09, Scope of Modification Accounting , which amended Accounting Standards Code Topic 718. FASB issued ASU 2017‑09 to reduce the cost and complexity when applying Topic 718 and standardize the practice of applying Topic 718 to financial reporting. The ASU was not developed to fundamentally change the definition of a modification, but instead to provide guidance for what changes would qualify as a modification. ASU No. 2017‑09 will be effective for us for the quarter ending December 31, 2018. The company is currently evaluating the potential impact of adoption on the Company’s Consolidated financial statements. Accounting Pronouncements Recently Adopted The Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends ASC Topic 718, Compensation – Stock Compensation during the three months ended December 31, 2017. The ASU includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The adoption of this ASU did not have a significant impact on the Company's Consolidated financial statements. In January 2017, the FASB issued ASU 2017‑04, Simplifying the Test for Goodwill Impairment . This ASU simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures goodwill impairment loss by comparing the implied value of a reporting unit’s goodwill with the carrying amount of that goodwill. The amendments in this ASU are effective for the Company for the quarter ending December 31, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. ASU 2017-04 was early adopted by the Company for the year beginning October 1, 2017 and did not have a material impact on the Company's Consolidated financial statements.

Summary of Significant Accoun31

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule Of Estimated Useful Lives For Major Classes Of Depreciable Assets	Estimated useful lives for major classes of depreciable assets are as follows: Asset Class Estimated Useful Life Machinery and equipment 3 to 20 years Buildings and improvements 10 to 40 years Property, plant, and equipment consists of the following: September 30, 2017 December 31, 2017 Machinery and equipment $ 338,056 $ 345,820 Land and buildings 84,282 85,946 Construction in process 24,788 28,354 447,126 460,120 Less: accumulated depreciation (167,083 ) (178,613 ) $ 280,043 $ 281,507
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net	as of September 30, and December 31, 2017 , respectively. As the Company is obligated to absorb all risk of loss up to 100% of the joint venture partner's equity, TWO is fully consolidated within the Company's consolidated financial statements under ASC 810, Consolidation . The Company has not provided additional financial support to this entity which it is not contractually required to provide, and the Company does not have the ability to use the assets of TWO to settle obligations of the Company’s other subsidiaries. September 30, 2017 December 31, 2017 Current assets (including cash of $1,907 and $3,033) $ 12,006 $ 9,665 Property, plant and equipment 6,107 5,704 Goodwill 2,206 2,206 Other noncurrent assets 2,735 — Total liabilities (12,781 ) (6,885 ) Three Months Ended December 31, 2016 2017 Total revenues $ 4,071 $ 5,989 Total operating expenses (3,272 ) (4,574 ) Income from operations $ 799 $ 1,415

Acquisitions and Divestitures (

Acquisitions and Divestitures (Tables)	3 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The opening balance sheet for the acquisitions is summarized as follows. The opening balance sheets for ETS and Noble are considered final as of December 31, 2017. The Company is still reviewing the opening balance sheets for ADI and Olson and expects to be complete by June 30, 2018. ETS Noble ADI Olson Total Current Assets $ 782 $ 567 $ 10,721 $ 1,730 $ 13,800 Property, plant and equipment 376 390 719 841 2,326 Goodwill 5,650 3,576 39,365 3,813 52,404 Other intangible assets 3,953 3,370 12,594 3,456 23,373 Other noncurrent assets — — 1,971 — 1,971 Total asset acquired 10,761 7,903 65,370 9,840 93,874 Total liabilities assumed (31 ) (269 ) (9,812 ) (434 ) (10,546 ) Net assets acquired $ 10,730 $ 7,634 $ 55,558 $ 9,406 $ 83,328

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the Company’s financial assets and liabilities at fair value. The fair values related to the pension assets are determined using net asset value (NAV) as a practical expedient, or by information categorized in the fair value hierarchy level based on the inputs used to determine fair value. The reported carrying amounts of deferred compensation assets and liabilities and debt approximate their fair values. The Company uses interest rates and other relevant information generated by market transactions involving similar instruments to fair value these assets and liabilities, therefore all are classified as Level 2 within the valuation hierarchy. Net Asset Value Quoted Market Significant Other Significant As of September 30, 2017 Assets: Pension plan Cash $ — $ 16,024 $ — $ — Government Securities 3,206 — — — Liability Driven Investment 2,754 — — — Guernsey Unit Trust 932 — — — Global Absolute Return 2,139 — — — Deferred compensation plan assets Trust Assets — 2,146 — — Insurance — — 17,396 — Liabilities: Pension plan — — (34,803 ) — Deferred compensation plan liabilities — — (21,159 ) — Long‑term debt — — (912,471 ) — As of December 31, 2017 Assets: Pension plan Cash $ — $ 16,139 $ — $ — Government Securities 3,073 — — — Liability Driven Investment 3,360 — — — Guernsey Unit Trust 950 — — — Global Absolute Return 2,198 — — — Deferred compensation plan assets Trust Assets — 1,926 — — Insurance — — 17,935 — Liabilities: Pension plan — — (34,803 ) — Deferred compensation plan liabilities — — (22,615 ) — Long‑term debt — — (807,473 ) —

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Schedule of accounts receivable	Accounts receivable are summarized as follows: September 30, 2017 December 31, 2017 Accounts Receivable $ 248,742 $ 230,505 Allowance for Doubtful Accounts (3,494 ) (3,786 ) $ 245,248 $ 226,719

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory	The major classes of inventory, net are as follows: September 30, 2017 December 31, 2017 Raw materials and supplies $ 64,113 $ 68,273 Work in progress 16,425 19,313 Finished goods and products held for resale 44,402 45,211 Costs of unbilled projects 5,706 6,378 Reserves for excess and obsolete (10,599 ) (10,869 ) $ 120,047 $ 128,306

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	3 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Estimated useful lives for major classes of depreciable assets are as follows: Asset Class Estimated Useful Life Machinery and equipment 3 to 20 years Buildings and improvements 10 to 40 years Property, plant, and equipment consists of the following: September 30, 2017 December 31, 2017 Machinery and equipment $ 338,056 $ 345,820 Land and buildings 84,282 85,946 Construction in process 24,788 28,354 447,126 460,120 Less: accumulated depreciation (167,083 ) (178,613 ) $ 280,043 $ 281,507

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of goodwill are as follows: September 30, December 31, Balance at beginning of period $ 267,643 $ 321,913 Business combinations 52,404 0 Measurement period adjustment (301 ) 0 Foreign currency translation 2,167 (986 ) Balance at end of period $ 321,913 $ 320,927

Debt (Tables)

Debt (Tables)	3 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long‑term debt consists of the following: September 30, 2017 December 31, 2017 First Lien Term Facility, due December 20, 2024 $ 896,574 $ 794,583 Revolving Credit Facility, due January 15, 2019 — — Build Own Operate Financing, due June 30, 2024 6,930 6,677 Notes Payable, due June 30, 2018 to July 31, 2023 3,287 2,869 Total debt 906,791 804,129 Less unamortized discount and lender fees (16,942 ) (15,196 ) Total net debt 889,849 788,933 Less current portion (11,325 ) (11,033 ) Total long‑term debt $ 878,524 $ 777,900
Schedule of Aggregate Maturities of Long-term Debt	Aggregate maturities of all long‑term debt, including current portion of long‑term debt and excluding capital lease obligations as of September 30, 2017 , are presented below: Fiscal Year Remainder of 2018 $ 7,499 2019 9,503 2020 9,402 2021 9,429 2022 9,459 Thereafter 758,837 Total $ 804,129

Product Warranties (Tables)

Product Warranties (Tables)	3 Months Ended
	Dec. 31, 2017
Guarantees and Product Warranties [Abstract]
Schedule of product warranty liability	A reconciliation of the activity related to the accrued warranty, including both the current and long‑term portions, is as follows: Three Months Ended December 31, 2016 2017 Balance at beginning of the period $ 23,309 $ 17,274 Warranty provision for sales 1,085 1,522 Settlement of warranty claims (2,889) (2,563) Foreign currency and other (522) 71 Balance at end of the period $ 20,983 $ 16,304

Restructuring and Related Cha40

Restructuring and Related Charges (Tables)	3 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Schedule of restructuring components	The table below sets forth the amounts accrued for the restructuring components and related activity: Three Months Ended December 31, 2016 2017 Balance at beginning of the period $ 13,217 $ 3,542 Restructuring charges related to VSP 10,189 382 Charges related to other initiatives 1,283 3,744 Write off charge and other non‑cash activity (913) (244) Cash payments (10,178) (5,498) Other adjustments (92) 1 Balance at end of the period $ 13,506 $ 1,927

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of net benefit costs	Pension expense for the German and UK plans were as follows: Three Months Ended December 31, 2016 2017 Service cost $ 251 $ 233 Interest cost 77 118 Expected return on plan assets (38) (31) Amortization of actuarial losses 176 76 Pension expense for defined benefit plans $ 466 $ 396

Share Based Compensation (Table

Share Based Compensation (Tables)	3 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock options, activity	A summary of the stock option activity as of December 31, 2017 is presented below (amounts in thousands except per share amounts): Options Weighted Average Exercise Price/Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2017 9,060 $ 5.18 7.5 years $ 11,011 Granted — — Exercised — — Forfeited (11 ) 4.86 (10 ) Expired — — Outstanding at December 31, 2017 9,049 5.18 7.3 years $ 11,001 Options exercisable at December 31, 2017 5,306 $ 4.80 9.9 years $ 5,433
Schedule of Nonvested Share Activity	A summary of the status of the Company's non-vested stock options as of and for the three month period ended December 31, 2017 is presented below. Shares Weighted Average Grant Date Fair Value/Share Nonvested at September 30, 2017 4,335 $ 1.36 Granted — Vested (685 ) 0.97 Forfeited (11 ) 0.87 Nonvested at December 31, 2017 3,639 $ 1.44
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following is a summary of the RSU activity for the three months ended December 31, 2017. Shares Weighted Average Grant Date Fair Value/Share Outstanding at September 30, 2017 — $ — Granted 1,197 20.88 Outstanding at December 31, 2017 1,197 $ 20.88

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Aggregate Future Minimum Rental Payments for Operating Leases	Future minimum aggregate rental payments under non-cancelable operating leases are as follows: Operating Fiscal Year Remainder of 2018 $ 8,362 2019 9,766 2020 8,317 2021 6,362 2022 4,037 Thereafter 10,236 Total $ 47,080
Schedule of Future Minimum Lease Payments for Capital Leases	The following is a schedule showing the future minimum lease payments under capital leases by years and the present value of the minimum lease payments as of December 31, 2017 . Capital Fiscal Year Remainder of 2018 $ 7,962 2019 9,635 2020 7,596 2021 4,738 2022 2,976 Thereafter 1,573 Total 34,480 Less amount representing interest (at rates ranging from 2.15% to 3.65%) 3,359 Present value of net minimum capital lease payments 31,121 Less current installments of obligations under capital leases 10,304 Obligations under capital leases, excluding current installments $ 20,817
Schedule of Future Minimum Lease Payments Receivable under Operating Leases	As of December 31, 2017 , future minimum lease payments receivable under operating leases are as follows: Operating Fiscal year Remainder of 2018 $ 4,922 2019 4,608 2020 3,821 2021 1,786 2022 1,796 Thereafter 3,687 Future minimum lease payments $ 20,620

Accrued Expenses and Other Li44

Accrued Expenses and Other Liabilities (Tables)	3 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued expenses and other liabilities consisted of the following: September 30, 2017 December 31, 2017 Salaries, wages and other benefits $ 52,116 $ 27,051 Severance payments 3,542 1,927 Taxes, other than income 9,244 10,039 Obligation under capital leases 9,777 10,304 Third party commissions 6,968 5,945 Insurance liabilities 4,915 6,092 Provisions for litigation 4,715 1,056 Earn outs related to acquisitions 4,304 4,304 Other 26,342 22,075 $ 121,923 $ 88,793

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	Three Months Ended December 31, 2016 2017 Total sales Industrial $ 147,005 $ 168,269 Municipal 69,385 69,313 Products 78,967 81,552 Total sales 295,357 319,134 Intersegment sales Industrial 1,299 3,075 Municipal 6,754 7,407 Products 7,432 11,601 Total intersegment sales 15,485 22,083 Sales to external customers Industrial 145,706 165,194 Municipal 62,631 61,906 Products 71,535 69,951 Total sales 279,872 297,051 Earnings before interest, taxes, depreciation and amortization (EBITDA) Industrial 32,001 40,127 Municipal 8,562 6,592 Products 14,918 10,699 Corporate (42,376 ) (27,707 ) Total EBITDA 13,105 29,711 Depreciation and amortization Industrial 8,912 10,145 Municipal 2,076 1,799 Products 3,522 2,985 Corporate 4,137 4,954 Total depreciation and amortization 18,647 19,883 (Loss) income from operations Industrial 23,089 29,982 Municipal 6,486 4,793 Products 11,396 7,714 Corporate (46,513 ) (32,661 ) Total (loss) income from operations (5,542 ) 9,828 Interest expense (14,753 ) (17,243 ) Loss before income taxes (20,295 ) (7,415 ) Income tax benefit 7,095 4,410 Net loss $ (13,200 ) $ (3,005 ) Capital expenditures Industrial $ 10,998 $ 8,948 Products 985 1,182 Municipal 596 1,747 Corporate 1,024 3,380 Total Capital expenditures $ 13,603 $ 15,257 September 30, December 31, Assets Industrial $ 461,471 $ 470,035 Municipal 155,698 147,925 Products 513,941 518,759 Corporate 342,199 342,190 Total assets $ 1,473,309 $ 1,478,909 Goodwill Industrial $ 128,190 $ 127,132 Municipal 9,865 9,880 Products 183,858 183,915 Total goodwill $ 321,913 $ 320,927

Earnings per share (Tables)

Earnings per share (Tables)	3 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	The following table sets forth the computation of basic and diluted loss from continuing operations per common share (in thousands, except per share amounts): Three Months Ended December 31, 2016 2017 Numerator: Numerator for basic and diluted loss per common share—Net (loss) income attributable to Evoqua Water Technologies $ (13,599 ) $ (3,713 ) Denominator: Denominator for basic net (loss) income per common share—weighted average shares 104,782 109,974 Effect of dilutive securities: Share‑based compensation — — Denominator for diluted net loss per common share—adjusted weighted average shares 104,782 109,974 Basic (loss) income attributable to Evoqua Water Technologies per common share $ (0.13 ) $ (0.03 ) Diluted (loss) income attributable to Evoqua Water Technologies per common share $ (0.13 ) $ (0.03 )

Description of the Company an47

Description of the Company and Basis of Presentation (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Nov. 07, 2017shares	Nov. 06, 2017$ / sharesshares	Jan. 16, 2014USD ($)	Dec. 31, 2017$ / shares	Dec. 31, 2017segment$ / shares	Dec. 31, 2017USD ($)$ / shares	Sep. 30, 2017$ / shares
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in USD per share) | $ / shares				$ 0.01	$ 0.01	$ 0.01	$ 0.01
Repayments of debt | $						$ 104,936
Number of reportable segments				3	3
IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction		27,777
Common stock, par value (in USD per share) | $ / shares		$ 0.01
Proceeds from issuance of common stock | $						$ 137,605
Initial Public Offering - Shares from Existing Shareholders [Member]
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction		8,333
Initial Public Offering - Shares from The Company [Member]
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction		19,444
Over-Allotment Option [Member]
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction	4,167
EWT Holdings II Corp and EWT Holdings III Corp [Member]
Subsidiary, Sale of Stock [Line Items]
Stock purchase price, net of cash received | $			$ 730,577

Summary of Significant Accoun48

Summary of Significant Accounting Policies (Details) - USD ($) shares in Thousands, $ in Thousands	1 Months Ended			3 Months Ended
	Dec. 31, 2017	Nov. 30, 2017	Oct. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Oct. 28, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of debt issuance costs and discounts				$ 848	$ 1,498
Write off of deferred debt issuance cost	$ 1,150	$ 1,844	$ 2,075	2,944	2,075
Prepayment of debt		$ 100,000
Revenues, percentage of completion method				59,387	47,063
Revenues, completed contract method				6,383	8,792
Foreign currency losses (gains) on intracompany loans				1,384	(7,245)
Research and development costs				$ 4,653	$ 5,005
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life				1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life				26 years
Machinery and equipment | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Property, plant and equipment, useful life				3 years
Machinery and equipment | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Property, plant and equipment, useful life				20 years
Building and Building Improvements [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Property, plant and equipment, useful life				10 years
Building and Building Improvements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Property, plant and equipment, useful life				40 years
Restricted Stock Units (RSUs) [Member]
Finite-Lived Intangible Assets [Line Items]
Stock issued during period, employee stock ownership plan (shares)				1,197
Stock issued during period, employee stock ownership plan				$ 25,000
Tack-On Financing Completed October 28, 2016 [Member]
Finite-Lived Intangible Assets [Line Items]
Debt instrument, fee amount						$ 481
December Refinancing [Member]
Finite-Lived Intangible Assets [Line Items]
Debt instrument, fee amount	$ 2,131			$ 2,131

Summary of Significant Accoun49

Summary of Significant Accounting Policies - Treated Water Outsourcing (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Subsidiary or Equity Method Investee [Line Items]
Current assets (including cash of $1,907 and $3,033)	$ 520,436		$ 512,240
Cash	3,033		1,907
Property, plant and equipment	281,507		280,043
Goodwill	320,927		321,913	$ 267,643
Other noncurrent assets	23,503		22,399
Total liabilities	(1,126,187)		(1,256,734)
Total revenues	297,051	$ 279,872
Income from operations	29,711	13,105
Treated Water Outsourcing [Member]
Subsidiary or Equity Method Investee [Line Items]
Current assets (including cash of $1,907 and $3,033)	9,665		12,006
Property, plant and equipment	5,704		6,107
Goodwill	2,206		2,206
Other noncurrent assets	0		2,735
Total liabilities	(6,885)		$ (12,781)
Total revenues	5,989	4,071
Total operating expenses	(4,574)	(3,272)
Income from operations	$ 1,415	$ 799

Acquisitions and Divestitures -

Acquisitions and Divestitures - Narrative (Details) CAD in Thousands, $ in Thousands	Nov. 01, 2017employee	Jun. 30, 2017CADcountry	Jun. 30, 2017USD ($)	May 09, 2017USD ($)	Nov. 01, 2016USD ($)	Dec. 31, 2017	Jun. 30, 2017USD ($)country
Business Acquisition [Line Items]
Number of countries in which entity operates						7
Environmental Treatment Services Inc.
Business Acquisition [Line Items]
Stock purchase price, net of cash received					$ 10,730
Number of employees | employee	10
Environmental Treatment Services Inc. | General and Administrative Expense
Business Acquisition [Line Items]
Transaction costs					$ 16
Noble Water Technologies
Business Acquisition [Line Items]
Stock purchase price, net of cash received				$ 7,634
Payments to acquire businesses, gross				5,915
Consideration transferred, liabilities incurred				1,719
Contingent consideration arrangements, range of outcomes, value, high				2,366
Noble Water Technologies | General and Administrative Expense
Business Acquisition [Line Items]
Transaction costs				$ 116
ADI Group, Inc.
Business Acquisition [Line Items]
Stock purchase price, net of cash received		CAD 72,220	$ 55,558
Number of employees		260	260
Payments to acquire businesses, gross		CAD 67,320	$ 51,785
Consideration transferred, liabilities incurred		4,900	3,773
Contingent consideration arrangements, range of outcomes, value, high		CAD 7,480					$ 5,760
Number of countries in which entity operates | country		35					35
ADI Group, Inc. | General and Administrative Expense
Business Acquisition [Line Items]
Transaction costs							$ 109
Olson Irrigation Systems
Business Acquisition [Line Items]
Stock purchase price, net of cash received			$ 9,406
Olson Irrigation Systems | General and Administrative Expense
Business Acquisition [Line Items]
Transaction costs							$ 140

Acquisitions and Divestitures51

Acquisitions and Divestitures - Balance Sheet for Acquisitions (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Goodwill	$ 320,927	$ 321,913	$ 267,643
Environmental Treatment Services Inc.
Business Acquisition [Line Items]
Current Assets	782
Property, plant and equipment	376
Goodwill	5,650
Other intangible assets	3,953
Other noncurrent assets	0
Total asset acquired	10,761
Total liabilities assumed	(31)
Net assets acquired	10,730
Noble Water Technologies
Business Acquisition [Line Items]
Current Assets	567
Property, plant and equipment	390
Goodwill	3,576
Other intangible assets	3,370
Other noncurrent assets	0
Total asset acquired	7,903
Total liabilities assumed	(269)
Net assets acquired	7,634
ADI Group, Inc.
Business Acquisition [Line Items]
Current Assets	10,721
Property, plant and equipment	719
Goodwill	39,365
Other intangible assets	12,594
Other noncurrent assets	1,971
Total asset acquired	65,370
Total liabilities assumed	(9,812)
Net assets acquired	55,558
Olson Irrigation Systems
Business Acquisition [Line Items]
Current Assets	1,730
Property, plant and equipment	841
Goodwill	3,813
Other intangible assets	3,456
Other noncurrent assets	0
Total asset acquired	9,840
Total liabilities assumed	(434)
Net assets acquired	9,406
2018 Acquisitions
Business Acquisition [Line Items]
Current Assets	13,800
Property, plant and equipment	2,326
Goodwill	52,404
Other intangible assets	23,373
Other noncurrent assets	1,971
Total asset acquired	93,874
Total liabilities assumed	(10,546)
Net assets acquired	$ 83,328

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Fair Value, Inputs, Level 1 [Member]
Deferred compensation plan assets
Trust Assets	$ 1,926	$ 2,146
Insurance	0	0
Liabilities:
Pension plan	0	0
Deferred compensation plan liabilities	0	0
Long‑term debt	0	0
Fair Value, Inputs, Level 2 [Member]
Deferred compensation plan assets
Trust Assets	0	0
Insurance	17,935	17,396
Liabilities:
Pension plan	(34,803)	(34,803)
Deferred compensation plan liabilities	(22,615)	(21,159)
Long‑term debt	(807,473)	(912,471)
Fair Value, Inputs, Level 3 [Member]
Deferred compensation plan assets
Trust Assets	0	0
Insurance	0	0
Liabilities:
Pension plan	0	0
Deferred compensation plan liabilities	0	0
Long‑term debt	0	0
Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Defined benefit plan, fair value of plan assets	16,139	16,024
Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Defined benefit plan, fair value of plan assets	0	0
Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Defined benefit plan, fair value of plan assets	0	0
US Government Agencies Debt Securities [Member]
Assets:
Plan assets at net asset value	3,073	3,206
Liability Driven Investment [Member]
Assets:
Plan assets at net asset value	3,360	2,754
Guernsey Unit Trust [Member]
Assets:
Plan assets at net asset value	950	932
Global Absolute Return [Member]
Assets:
Plan assets at net asset value	$ 2,198	$ 2,139

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Receivables [Abstract]
Accounts Receivable	$ 230,505	$ 248,742
Allowance for Doubtful Accounts	(3,786)	(3,494)
Accounts receivable, net	$ 226,719	$ 245,248

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 68,273	$ 64,113
Work in progress	19,313	16,425
Finished goods and products held for resale	45,211	44,402
Costs of unbilled projects	6,378	5,706
Reserves for excess and obsolete	(10,869)	(10,599)
Inventory, Net	$ 128,306	$ 120,047

Property, Plant, and Equipmen55

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 14,007	$ 12,427
Maintenance and repair expense	5,814	$ 5,155
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	460,120		$ 447,126
Less: accumulated depreciation	(178,613)		(167,083)
Property, plant and equipment, net	281,507		280,043
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	345,820		338,056
Land and buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	85,946		84,282
Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 28,354		$ 24,788

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017
Segment Reporting Information [Line Items]
Goodwill deductible for tax purposes	$ 120,832	$ 139,581
Neptune Benson Reporting Unit [Member]
Segment Reporting Information [Line Items]
Reporting unit, percentage of fair value in excess of carrying amount			3.00%

Goodwill Schedule of Goodwill (

Goodwill Schedule of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017
Goodwill [Roll Forward]
Goodwill, beginning of the period	$ 321,913	$ 267,643
Business combinations	0	52,404
Measurement period adjustment	0	(301)
Foreign currency translation	(986)	2,167
Goodwill, end of the period	$ 320,927	$ 321,913

Debt (Details)

Debt (Details) - USD ($)	Jan. 15, 2014	Dec. 31, 2017	Sep. 30, 2017	Dec. 19, 2017	Aug. 08, 2017	Jun. 30, 2017	Oct. 28, 2016
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount		$ 17,274,000	$ 18,772,000
Debt instrument, periodic payment, principal		1,991,000
Unamortized discount (premium) and debt issuance costs, net		15,196,000	16,942,000
Long-term debt, gross		804,129,000	906,791,000
Notes payable		2,869,000	3,287,000
Term Loan [Member]
Line of Credit Facility [Line Items]
Line of credit facility, outstanding amount				$ 796,574,000
Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		125,000,000
Line of credit facility, remaining borrowing capacity		125,000,000	95,000,000
Debt instrument, unused borrowing capacity, amount		118,466,000	88,294,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			35,000,000
Letters of credit outstanding, amount		$ 6,534,000	6,706,000
Minimum [Member]
Line of Credit Facility [Line Items]
Debt instrument, interest rate, stated percentage		6.26%
Maximum [Member]
Line of Credit Facility [Line Items]
Debt instrument, interest rate, stated percentage		7.39%
First Lien Term Facility, due December 20, 2024
Line of Credit Facility [Line Items]
Debt instrument, term	7 years
Unamortized discount (premium) and debt issuance costs, net		$ 15,196,000	$ 16,942,000
First Lien Term Facility, due December 20, 2024 | Term Loan [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 505,000,000
First Lien Term Facility, due December 20, 2024 | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	75,000,000
Letters of credit outstanding, amount					$ 230,000,000
Line of credit facility, current borrowing capacity							$ 95,000,000
First Lien Term Facility, due December 20, 2024 | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 35,000,000
Existing Term Loans [Member]
Line of Credit Facility [Line Items]
Prepayment penalty for refinancing (percent)		1.00%
Second Lien Term Facility
Line of Credit Facility [Line Items]
Debt instrument, term	8 years
Second Lien Term Facility | Term Loan [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 75,000,000
2022 Borrowings | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 87,500,000
Line of credit facility, interest rate at period end		6.25%
Variable rate basis interest rate at period end		4.50%
2019 Borrowings | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 37,500,000
Line of credit facility, interest rate at period end		6.75%	6.50%
Variable rate basis interest rate at period end		4.50%	4.25%
Base Rate [Member] | 2022 Borrowings | Minimum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		1.50%
Base Rate [Member] | 2022 Borrowings | Maximum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		2.75%
Base Rate [Member] | 2019 Borrowings | Minimum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate			2.00%
Base Rate [Member] | 2019 Borrowings | Maximum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate			3.25%
Prime Rate [Member] | 2022 Borrowings | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		1.75%
Prime Rate [Member] | 2019 Borrowings | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		2.25%
London Interbank Offered Rate (LIBOR) [Member] | Build Own Operate Financing, due June 30, 2024
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.00%
Line of Credit [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 45,000,000	$ 35,000,000
Letters of credit outstanding, amount		$ 12,238,000	10,568,000
Loans Payable | Build Own Operate Financing, due June 30, 2024
Line of Credit Facility [Line Items]
Debt instrument, term		7 years
Debt instrument, periodic payment, principal		$ 254,000
Debt instrument, fee amount						$ 50,000
Debt instrument, interest rate, stated percentage		5.08%
Debt instrument, face amount						$ 7,100,000
Long-term debt, gross		$ 6,677,000	$ 6,930,000
Ratings Condition Period [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		2.75%
Ratings Condition Period [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.75%
Other than Ratings Condition Period [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.00%
Other than Ratings Condition Period [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.75%
First Lien Net Leverage Ration Exceeds 2.5X [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		2.75%
First Lien Net Leverage Ration Exceeds 2.5X [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.25%
First Lien Net Leverage Ratio is Less than or Equal to 2.5X [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		2.50%
First Lien Net Leverage Ratio is Less than or Equal to 2.5X [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Revolving Credit Facility, due January 15, 2019
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		3.00%

Debt Schedule of Long-term Debt

Debt Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Debt Instrument [Line Items]
Total debt	$ 804,129	$ 906,791
Less unamortized discount and lender fees	(15,196)	(16,942)
Total net debt	788,933	889,849
Current portion of debt	(11,033)	(11,325)
Total long‑term debt	777,900	878,524
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Total debt	794,583	896,574
Revolving Credit Facility, due January 15, 2019
Debt Instrument [Line Items]
Total debt	0	0
Notes Payable, due June 30, 2018 to July 31, 2023
Debt Instrument [Line Items]
Total debt	2,869	3,287
Build Own Operate Financing, due June 30, 2024 | Loans Payable
Debt Instrument [Line Items]
Total debt	$ 6,677	$ 6,930

Debt Long-term Debt Maturities

Debt Long-term Debt Maturities (Details) $ in Thousands	Sep. 30, 2017USD ($)
Debt Disclosure [Abstract]
Remainder of 2018	$ 7,499
2,019	9,503
2,020	9,402
2,021	9,429
2,022	9,459
Thereafter	758,837
Long-term Debt	$ 804,129

Product Warranties (Details)

Product Warranties (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty accrual, beginning of the period	$ 17,274	$ 23,309
Warranty provision for sales	1,522	1,085
Settlement of warranty claims	(2,563)	(2,889)
Settlement of warranty claims	71	(522)
Product warranty accrual, end of the period	$ 16,304	$ 20,983

Restructuring and Related Cha62

Restructuring and Related Charges (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of the period	$ 3,542	$ 13,217
Restructuring charges related to VSP	382	10,189
Charges related to other initiatives	3,744	1,283
Write off charge and other non‑cash activity	(244)	(913)
Cash payments	(5,498)	(10,178)
Other adjustments	1	(92)
Restructuring reserve, end of the period	$ 1,927	$ 13,506

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Service cost	$ 233	$ 251
Interest cost	118	77
Expected return on plan assets	(31)	(38)
Amortization of actuarial losses	76	176
Pension expense for defined benefit plans	$ 396	$ 466

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018
Income Tax Contingency [Line Items]
Tax cuts and jobs act of 2017, provisional income tax (expense) benefit	$ 3,500
Estimated annual effective tax rate used to calculate income tax expense (benefit)	15.60%	34.90%
Extraterritorial income exclusion, percent	0.20%	8.10%
Change in deferred tax assets valuation allowance, percent		2.00%
Federal statutory income tax rate, percent	24.50%
Effective income tax rate reconciliation, percent	59.50%
Income tax (benefit) expense	$ 4,410	$ 7,095
Loss before income taxes	$ (7,415)	$ (20,295)
Scenario, Forecast [Member]
Income Tax Contingency [Line Items]
Effective income tax rate reconciliation, percent			15.60%

Share Based Compensation - Narr

Share Based Compensation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 2,612	$ 466
Compensation cost not yet recognized, period for recognition	22,917
Fair value of options vested	663
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized, period for recognition	$ 3,454
Period for recognition for unrecognized compensation expense	3 years 8 months
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition for unrecognized compensation expense	1 year 10 months
Stock-settled RSU's (shares)	1,197,000		0
Aggregate value	$ 25,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan, number of shares authorized (shares)	5,100,000
Equity incentive plan, shares issued in period	0
Evoqua Water Technologies Corp. Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
Stock awards vesting percentage	25.00%

Share Based Compensation - Stoc

Share Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of the period (shares)			9,060,000
Granted (shares)			0
Exercised (shares)			0
Forfeited (shares)			(11,000)
Expired (shares)			0
Outstanding at end of the period (shares)	9,049,000	9,060,000	9,049,000
Options exercisable (shares)	5,306,000		5,306,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, outstanding, beginning balance (in dollars per share)			$ 5.18
Weighted average exercise price, granted (in dollars per share)			0
Weighted average exercise price, exercised (in dollars per share)			0
Weighted average exercise price, forfeited (in dollars per share)			4.86
Weighted average exercise price, expired (in dollars per share)			0
Weighted average exercise price, outstanding, ending balance (in dollars per share)	$ 5.18	$ 5.18	5.18
Weighted average exercise price, exercisable (in dollars per share)	$ 4.80		$ 4.80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term, outstanding	7 years 4 months	7 years 6 months
Weighted average contractual term, exercisable			9 years 11 months
Intrinsic value, outstanding	$ 11,001	$ 11,011	$ 11,001
Intrinsic value, forfeited			$ (10,000)
Intrinsic value, exercisable	$ 5,433		$ 5,433

Share Based Compensation - Nonv

Share Based Compensation - Nonvested Share Activity (Details)	3 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at September 30, 2017 | shares	4,335,000
Granted (shares) | shares	0
Vested (shares) | shares	(685,000)
Forfeited (shares) | shares	(11,000)
Nonvested at December 31, 2017 | shares	3,639,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, nonvested, beginning balance (in dollars per share) | $ / shares	$ 1.36
Weighted average grant date fair value, granted (in dollars per share) | $ / shares
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	0.97
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	0.87
Weighted average grant date fair value, nonvested, ending balance (in dollars per share) | $ / shares	$ 1.44

Share Based Compensation - RSU

Share Based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	3 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding at beginning of the period (shares) | shares	0
Stock granted during period, employee stock ownership plan (shares) | shares	1,197
Outstanding at beginning of the period | shares	1,197
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, nonvested, equity instruments other than options, beginning of the period (in dollar per share) | $ / shares	$ 0
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	20.88
Weighted average grant date fair value, nonvested, equity instruments other than options, end of the period (in dollar per share) | $ / shares	$ 20.88

Concentration of Credit Risk (D

Concentration of Credit Risk (Details)	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Number of countries in which entity operates	7

Related_Party Transactions (Det

Related‑Party Transactions (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2017USD ($)
Related Party Transaction [Line Items]
Number of affiliates	2
Line of credit facility, lender	1
AEA Investors LP [Member]
Related Party Transaction [Line Items]
Due to related parties	$ 38		$ 0
Related party commitment	14,409		16,218
Advisory Fees [Member] | AEA Investors LP [Member]
Related Party Transaction [Line Items]
Fees paid to related party	333	$ 1,000
Other Expense [Member] | AEA Investors LP [Member]
Related Party Transaction [Line Items]
Expenses from transactions with related party	33	57
Customer [Member]
Related Party Transaction [Line Items]
Revenue from related parties	296	$ 175
Accounts receivable, related parties	$ 1,063		$ 2,354

Commitments and Contingencies71

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Operating Leased Assets [Line Items]
Letters of credit outstanding, amount	$ 17,274		$ 18,772
Rent expense	3,113	$ 2,772
Equipment [Member]
Operating Leased Assets [Line Items]
Capital leased assets, gross	46,063		43,727
Capital leases, carrying value	30,531		30,302
Letter of Credit [Member]
Operating Leased Assets [Line Items]
Letters of credit outstanding, amount	6,534		6,706
Surety Bond [Member]
Operating Leased Assets [Line Items]
Surety bonds	87,849		90,985
Siemens [Member]
Operating Leased Assets [Line Items]
Letters of credit outstanding, amount	901		909
Siemens [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Surety bonds	$ 12,970		$ 12,967
Minimum [Member]
Operating Leased Assets [Line Items]
Lessor, operating lease, term of contract	5 years
Minimum [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Financial instruments, commitments, expiration period	12 months
Maximum [Member]
Operating Leased Assets [Line Items]
Lessor, operating lease, term of contract	20 years
Maximum [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Financial instruments, commitments, expiration period	10 years

Commitments and Contingencies F

Commitments and Contingencies Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2018	$ 8,362
2,019	9,766
2,020	8,317
2,021	6,362
2,022	4,037
Thereafter	10,236
Total	$ 47,080

Commitments and Contingencies73

Commitments and Contingencies Future Minimum Rental Payments under Capital Lease (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Capital Leased Assets [Line Items]
Remainder of 2018	$ 7,962
2,019	9,635
2,020	7,596
2,021	4,738
2,022	2,976
Thereafter	1,573
Total	34,480
Capital Leases, Future Minimum Payments, Interest Included in Payments	3,359
Present value of net minimum capital lease payments	31,121
Obligation under capital leases	10,304	$ 9,777
Obligations under capital leases, excluding current installments	$ 20,817
Capital lease obligations | Minimum [Member]
Capital Leased Assets [Line Items]
Capital leases of lessee, basis spread on variable rate	2.15%
Capital lease obligations | Maximum [Member]
Capital Leased Assets [Line Items]
Capital leases of lessee, basis spread on variable rate	3.65%

Commitments and Contingencies74

Commitments and Contingencies Future Minimum Lease Payments Receivable under Operating Leases (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2018	$ 4,922
2,019	4,608
2,020	3,821
2,021	1,786
2,022	1,796
Thereafter	3,687
Future minimum lease payments	$ 20,620

Accrued Expenses and Other Li75

Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Payables and Accruals [Abstract]
Salaries, wages and other benefits	$ 27,051	$ 52,116
Severance payments	1,927	3,542
Taxes, other than income	10,039	9,244
Obligation under capital leases	10,304	9,777
Third party commissions	5,945	6,968
Insurance liabilities	6,092	4,915
Provisions for litigation	1,056	4,715
Earn outs related to acquisitions	4,304	4,304
Other	22,075	26,342
Accrued expenses and other liabilities	$ 88,793	$ 121,923

Business Segments (Details)

Business Segments (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Segment Reporting [Abstract]
Number of reportable segments	3	3
Segment Reporting Information [Line Items]
Revenue from product sales and services			$ 297,051	$ 279,872
Sales to external customers			297,051	279,872
Earnings before interest, taxes, depreciation and amortization (EBITDA)			29,711	13,105
Depreciation and amortization			19,883	18,647
(Loss) income from operations			9,828	(5,542)
Interest expense			(17,243)	(14,753)
Loss before income taxes			(7,415)	(20,295)
Income tax benefit (expense)			4,410	7,095
Net (loss) income			(3,005)	(13,200)
Capital expenditures			15,257	13,603
Assets	$ 1,478,909	$ 1,478,909	1,478,909		$ 1,473,309
Goodwill	320,927	320,927	320,927		321,913	$ 267,643
Industrial [Member]
Segment Reporting Information [Line Items]
Capital expenditures			8,948	10,998
Municipal [Member]
Segment Reporting Information [Line Items]
Capital expenditures			1,747	596
Product [Member]
Segment Reporting Information [Line Items]
Capital expenditures			1,182	985
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			22,083	15,485
Intersegment Eliminations [Member] | Industrial [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			3,075	1,299
Intersegment Eliminations [Member] | Municipal [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			7,407	6,754
Intersegment Eliminations [Member] | Product [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			11,601	7,432
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			319,134	295,357
Operating Segments [Member] | Industrial [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			168,269	147,005
Sales to external customers			165,194	145,706
Earnings before interest, taxes, depreciation and amortization (EBITDA)			40,127	32,001
Depreciation and amortization			10,145	8,912
(Loss) income from operations			29,982	23,089
Assets	470,035	470,035	470,035		461,471
Goodwill	127,132	127,132	127,132		128,190
Operating Segments [Member] | Municipal [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			69,313	69,385
Sales to external customers			61,906	62,631
Earnings before interest, taxes, depreciation and amortization (EBITDA)			6,592	8,562
Depreciation and amortization			1,799	2,076
(Loss) income from operations			4,793	6,486
Assets	147,925	147,925	147,925		155,698
Goodwill	9,880	9,880	9,880		9,865
Operating Segments [Member] | Product [Member]
Segment Reporting Information [Line Items]
Revenue from product sales and services			81,552	78,967
Sales to external customers			69,951	71,535
Earnings before interest, taxes, depreciation and amortization (EBITDA)			10,699	14,918
Depreciation and amortization			2,985	3,522
(Loss) income from operations			7,714	11,396
Assets	518,759	518,759	518,759		513,941
Goodwill	183,915	183,915	183,915		183,858
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Earnings before interest, taxes, depreciation and amortization (EBITDA)			(27,707)	(42,376)
Depreciation and amortization			4,954	4,137
(Loss) income from operations			(32,661)	(46,513)
Capital expenditures			3,380	$ 1,024
Assets	$ 342,190	$ 342,190	$ 342,190		$ 342,199

Earnings per share (Details)

Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Numerator for basic and diluted loss per common share—Net (loss) income attributable to Evoqua Water Technologies	$ (3,713)	$ (13,599)
Denominator:
Denominator for basic net (loss) income per common share—weighted average shares	109,974	104,782
Effect of dilutive securities:
Share‑based compensation	0	0
Denominator for diluted net loss per common share—adjusted weighted average shares	109,974	104,782
Basic (loss) earnings per common share (in dollars per share)	$ (0.03)	$ (0.13)
Diluted (loss) earnings per common share (in dollars per share)	$ (0.03)	$ (0.13)
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	10,246	9,012

Subsequent Events (Details)

Subsequent Events (Details) - Pure Water Solutions [Member] - Subsequent Event [Member] $ in Thousands	Feb. 01, 2018USD ($)
Subsequent Event [Line Items]
Stock purchase price, net of cash received	$ 993
Payments to acquire businesses, gross	3,706
Consideration transferred, liabilities incurred	$ 4,699