Evoqua Water Technologies (AQUA) 10-Q 1 Feb 22 2022 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Dec. 31, 2021	Jan. 31, 2022
Cover [Abstract]
Amendment Flag	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Type	10-Q
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-38272
Entity Registrant Name	EVOQUA WATER TECHNOLOGIES CORP.
Entity Tax Identification Number	46-4132761
Entity Address, Address Line One	210 Sixth Avenue
Entity Address, Postal Zip Code	15222
Entity Address, City or Town	Pittsburgh,
Entity Address, State or Province	PA
City Area Code	724
Local Phone Number	772-0044
Trading Symbol	AQUA
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		120,850,046
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2022
Entity Central Index Key	0001604643
Current Fiscal Year End Date	--09-30

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
ASSETS
Current assets	$ 681,902	$ 678,458
Cash and cash equivalents	152,525	146,244
Receivables, net	236,923	277,995
Inventories, net	174,271	158,503
Contract assets	84,982	72,746
Prepaid and other current assets	32,092	21,871
Income tax receivable	1,109	1,099
Property, plant, and equipment, net	373,073	374,988
Goodwill	407,521	407,376
Intangible assets, net	281,357	290,075
Deferred income taxes, net of valuation allowance	8,192	8,285
Operating lease right-of-use assets, net	43,474	45,521
Other non‑current assets	72,082	64,188
Total assets	1,867,601	1,868,891
LIABILITIES AND EQUITY
Current liabilities	398,490	405,989
Accounts payable	175,873	164,535
Current portion of debt, net of deferred financing fees and discounts	13,296	12,775
Contract liabilities	53,022	55,883
Product warranties	7,893	8,138
Accrued expenses and other liabilities	144,444	160,367
Income tax payable	3,962	4,291
Non‑current liabilities	866,518	880,683
Long-term debt, net of deferred financing fees and discounts	716,947	730,430
Product warranties	2,902	2,966
Obligation under operating leases	35,938	37,935
Other non‑current liabilities	94,029	92,909
Deferred income taxes	16,702	16,443
Total liabilities	1,265,008	1,286,672
Commitments and Contingent Liabilities (Note 19)
Shareholders’ equity
Common stock, par value $0.01: authorized 1,000,000 shares; issued 122,372 shares, outstanding 120,708 at December 31, 2021; issued 122,173 shares, outstanding 120,509 at September 30, 2021	1,225	1,223
Treasury stock: 1,664 shares at December 31, 2021 and 1,664 shares at September 30, 2021	(2,837)	(2,837)
Additional paid-in capital	588,077	582,052
Retained deficit	(5,195)	(11,182)
Accumulated other comprehensive income, net of tax	19,774	11,415
Total Evoqua Water Technologies Corp. equity	601,044	580,671
Non-controlling interest	1,549	1,548
Total shareholders’ equity	602,593	582,219
Total liabilities and shareholders’ equity	$ 1,867,601	$ 1,868,891

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Sep. 30, 2021
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, issued (in shares)	122,372,000	122,173,000
Common stock, outstanding (in shares)	120,708,000	120,509,000
Treasury stock (in shares)	1,664,000	1,664,000

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenues [Abstract]
Revenue from product sales and services	$ 366,268	$ 322,193
Cost of Revenue [Abstract]
Cost of product sales and services	(255,760)	(226,848)
Gross profit	110,508	95,345
Operating Expenses [Abstract]
General and administrative expense	(57,829)	(42,283)
Sales and marketing expense	(36,449)	(33,928)
Research and development expense	(3,452)	(3,123)
Total operating expenses	(97,730)	(79,334)
Other operating income	1,657	480
Other operating expense	(147)	(257)
Operating profit (loss)	14,288	16,234
Interest expense	(6,579)	(8,673)
Income before income taxes	7,709	7,561
Income tax expense	(1,621)	(1,084)
Net income	6,088	6,477
Net income attributable to Evoqua Water Technologies Corp.	$ 5,987	$ 6,433
Basic income per common share	$ 0.05	$ 0.05
Diluted income per common share	$ 0.05	$ 0.05
Non-controlling Interest
Operating Expenses [Abstract]
Net income	$ 101	$ 44
Net income attributable to non‑controlling interest	101	44
Revenue from product sales
Revenues [Abstract]
Revenue from product sales and services	212,568	180,015
Cost of Revenue [Abstract]
Cost of product sales and services	(153,795)	(131,061)
Revenue from service
Revenues [Abstract]
Revenue from product sales and services	153,700	142,178
Cost of Revenue [Abstract]
Cost of product sales and services	$ (101,965)	$ (95,787)

Unaudited Consolidated Statem_2

Unaudited Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Other comprehensive income (loss)
Net income	$ 6,088	$ 6,477
Foreign currency translation adjustments	1,609	(4,877)
Unrealized derivative gain on cash flow hedges, net of tax	6,581	1,002
Change in pension liability, net of tax	169	264
Total other comprehensive income (loss)	8,359	(3,611)
Less: Comprehensive income attributable to non‑controlling interest	(101)	(44)
Comprehensive income attributable to Evoqua Water Technologies Corp.	$ 14,346	$ 2,822

Unaudited Consolidated Statem_3

Unaudited Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive (Loss) Income	Non-controlling Interest
Common stock issued at the beginning of the period (shares) at Sep. 30, 2020		119,486,000
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2020	$ 482,063	$ 1,189	$ (2,837)	$ 564,928	$ (62,664)	$ (20,472)	$ 1,919
Treasury stock, balance at the beginning of the period (in shares) at Sep. 30, 2020			2,195,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity based compensation expense	3,019			3,019
Issuance of common stock (in shares)		1,264,000	1,000
Stock Issued During Period, Value, New Issues	14,263	$ 13		14,250
Dividends paid to non-controlling interest	(250)						(250)
Net income	6,477				6,433		44
Net income	(3,611)					(3,611)
Common stock issued at the end of the period (shares) at Dec. 31, 2020		120,750,000
Stockholders' equity, balance at the end of the period at Dec. 31, 2020	$ 501,961	$ 1,202	$ (2,837)	582,197	(56,231)	(24,083)	1,713
Treasury stock, balance at the end of the period (in shares) at Dec. 31, 2020			2,196,000
Common stock issued at the beginning of the period (shares) at Sep. 30, 2021	122,173,000	122,173,000
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2021	$ 582,219	$ 1,223	$ (2,837)	582,052	(11,182)	11,415	1,548
Treasury stock, balance at the beginning of the period (in shares) at Sep. 30, 2021	1,664,000		1,664,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity based compensation expense	$ 5,203			5,203
Issuance of common stock (in shares)		199,000	0
Stock Issued During Period, Value, New Issues	824	$ 2		822
Dividends paid to non-controlling interest	(100)						(100)
Net income	6,088				5,987		101
Net income	$ 8,359					8,359
Common stock issued at the end of the period (shares) at Dec. 31, 2021	122,372,000	122,372,000
Stockholders' equity, balance at the end of the period at Dec. 31, 2021	$ 602,593	$ 1,225	$ (2,837)	$ 588,077	$ (5,195)	$ 19,774	$ 1,549
Treasury stock, balance at the end of the period (in shares) at Dec. 31, 2021	1,664,000		1,664,000

Unaudited Consolidated Statem_4

Unaudited Consolidated Statements of Changes in Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net income	$ 6,088	$ 6,477
Reconciliation of net income to cash flows provided by operating activities:
Depreciation and amortization	28,640	27,391
Amortization of deferred financing fees (includes $0 and $0 write off of deferred financing fees)	467	526
Deferred income taxes	251	258
Share-based compensation	5,203	3,019
(Gain) loss on sale of property, plant, and equipment	(4)	19
Foreign currency exchange losses (gains) on intercompany loans and other non-cash items	1,502	(6,459)
Changes in assets and liabilities
Accounts receivable	41,309	18,083
Inventories	(16,021)	(11,551)
Contract assets	(12,189)	21,458
Prepaids and other current assets	(3,797)	(465)
Accounts payable	11,241	(12,652)
Accrued expenses and other liabilities	(16,953)	(24,701)
Contract liabilities	(2,887)	8,010
Income taxes	(338)	(1,271)
Other non‑current assets and liabilities	(6,132)	(4,873)
Net cash provided by operating activities	36,380	23,269
Investing activities
Purchase of property, plant, and equipment	(15,540)	(17,260)
Purchase of intangibles	(664)	(81)
Proceeds from sale of property, plant, and equipment	1,370	127
Acquisitions, net of cash received $0 and $0	0	(8,743)
Net cash used in investing activities	(14,834)	(25,957)
Financing activities
Issuance of debt, net of deferred issuance costs	5,949	7,805
Repayment of debt	(19,378)	(5,723)
Repayment of finance lease obligation	(3,174)	(3,821)
Proceeds from issuance of common stock	2,085	6,617
Taxes paid related to net share settlements of share-based compensation awards	(1,261)	(9)
Distribution to non‑controlling interest	(100)	(250)
Net cash (used in) provided by financing activities	(15,879)	4,619
Effect of exchange rate changes on cash	614	2,988
Change in cash and cash equivalents	6,281	4,919
Cash and cash equivalents
Beginning of period	146,244	193,001
End of period	152,525	197,920
Supplemental disclosure of cash flow information
Cash paid for taxes	1,654	1,334
Cash paid for interest	5,706	7,624
Non‑cash investing and financing activities
Finance lease transactions	2,700	5,484
Operating lease transactions	$ 1,152	$ 5,954

Unaudited Consolidated Statem_5

Unaudited Consolidated Statements of Changes in Cash Flows (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement of Cash Flows [Abstract]
Write off of deferred debt issuance cost	$ 0	$ 0
Cash acquired from acquisition	$ 0	$ 0

Description of the Company and

Description of the Company and Basis of Presentation	3 Months Ended
	Dec. 31, 2021
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. (referred to herein as the “Company” or “EWT”) is a holding company and does not conduct any business operations of its own. The Company was incorporated on October 7, 2013. On November 6, 2017, the Company completed its initial public offering (“IPO”). 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 branch network. Headquartered in Pittsburgh, Pennsylvania, EWT is a multinational corporation with operations in the United States (“U.S.”), Canada, the United Kingdom (“UK”), the Netherlands, Germany, Australia, the People’s Republic of China, Singapore, the Republic of Korea and India. The Company is organizationally structured into two reportable operating segments for the purpose of making operational decisions and assessing financial performance: (i) Integrated Solutions and Services and (ii) Applied Product Technologies. Basis of Presentation The accompanying Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”). All intercompany transactions have been eliminated. Unless otherwise specified, all dollar and share amounts in these notes are referred to in thousands. The interim Unaudited 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. In our opinion, all adjustments considered necessary for a fair presentation of the financial statements have been included, and all adjustments are of a normal and recurring nature. We consistently applied the accounting policies described in our Annual Report on Form 10-K for the fiscal year ended September 30, 2021, as filed with the SEC on November 17, 2021 (“2021 Annual Report”), in preparing these Unaudited Consolidated Financial Statements, with the exception of accounting standard updates described in Note 2, “Recent Accounting Pronouncements.” These Unaudited Consolidated Financial Statements should be read in conjunction with the audited financial statements and the notes included in our 2021 Annual Report. Certain prior period amounts have been reclassified to conform to the current period presentation. Correction of Immaterial Errors During the quarter ended March 31, 2021, the Company identified errors related to the reporting of tax remittances associated with certain equity awards, resulting in a classification error of $18,669 between additional paid in capital and accumulated other comprehensive loss. Management recorded the correction to additional paid in capital and accumulated other comprehensive balances during the quarter ended March 31, 2021. Management considered both the quantitative and qualitative factors within the provisions of SEC Staff Accounting Bulletin No. 99, Materiality , and Staff Accounting Bulletin No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements . Based on evaluation of the errors, management has concluded that the prior period errors were immaterial to the previously issued financial statements. As a result of that classification error, management also identified a second, related immaterial classification error for the understatement of net cash provided by operating cash flows of $7,655 and an overstatement of net cash provided by financing activities of $7,655 for the period from October 1, 2020 to December 31, 2020. The Company has elected to voluntarily correct the identified immaterial classification error in the prior period Unaudited Consolidated Statements of Changes to Cash Flows to enhance comparability. In doing so, balances in the Unaudited Consolidated Statements of Changes to Cash Flows included in this Form 10-Q have been adjusted to reflect the voluntary immaterial classification error correction of $7,655 between financing and operating in the prior period. The correction of the above classification errors did not have any effect on the Unaudited Consolidated Statements of Operations in any of the periods previously presented.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Not Yet Adopted In October 2021, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , which amends Accounting Standards Codification (“ASC”) 805 to require an acquirer to, at the date of acquisition, recognize and measure contract assets and contract liabilities acquired in accordance with ASU 2014-9, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) , as if the entity had originated the contracts, rather than adjust them to fair value at the acquisition date. The guidance is effective for fiscal years beginning after December 15, 2022 and is to be applied prospectively to business combinations occurring on or after the effective date of the amendments. The Company is currently assessing the impact of adoption on the Company’s Unaudited Consolidated Financial Statements and related disclosures. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , and also issued subsequent amendments to the initial guidance (collectively, “Topic 848”). Topic 848 became effective immediately and expires on December 31, 2022. Topic 848 allows eligible contracts that are modified to be accounted for as a continuation of those contracts, permits companies to preserve their hedge accounting during the transition period and enables companies to make a one-time election to transfer or sell held-to-maturity debt securities that are affected by rate reform. Topic 848 provides optional expedients and exceptions for contracts, hedging relationships and other transactions that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform if certain criteria are met. The Company is currently assessing the impact of adoption on the Company’s Unaudited Consolidated Financial Statements and related disclosures.

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Dec. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Variable Interest Entity Disclosure	Variable Interest Entities Treated Water Outsourcing (“TWO”) is a joint venture between the Company and Nalco Water, an Ecolab company, in which the Company holds a 50% partnership interest. The Company is obligated to absorb all risk of loss up to 100% of the joint venture partner’s equity. As such, the Company fully consolidates TWO as a variable interest entity (“VIE”) under ASC Topic No. 810, Consolidation . The Company has not provided, and is not contractually required to provide, additional financial support to this entity, and the Company does not have the ability to use the assets of TWO to settle obligations of the Company’s other subsidiaries. The following provides a summary of TWO’s balance sheet as of December 31, 2021 and September 30, 2021, and summarized financial information for the three months ended December 31, 2021 and 2020. December 31, September 30, Current assets (includes cash of $1,363 and $1,380) $ 3,272 $ 3,202 Property, plant, and equipment 842 903 Goodwill 2,206 2,206 Total liabilities (1,017) (1,009) Three Months Ended 2021 2020 Total revenue $ 845 $ 834 Total operating expenses (737) (737) Income from operations $ 108 $ 97 On October 1, 2019, the Company acquired a 60% investment position in San Diego-based Frontier Water Systems, LLC (“Frontier”). The Frontier acquisition is a VIE because it has insufficient equity to finance its activities due to key assets being assigned to the Company upon acquisition. The Company is the primary beneficiary of Frontier because the Company has the power to direct the activities that most significantly affect Frontier’s economic performance. In addition, the Company entered into an agreement to purchase the remaining 40% interest in Frontier on or prior to March 30, 2024. This agreement (a) gave holders of the remaining 40% interest in Frontier (the “Minority Owners”) the right to sell to Evoqua up to approximately 10% of the outstanding equity in Frontier at a predetermined price, which right was exercisable by the Minority Owners between January 1, 2021 and February 28, 2021 (the “Option”), and (b) obligates the Company to purchase and the Minority Owners to sell all of the Minority Owners’ remaining interest in Frontier at the fair market value at the time of sale on or prior to March 30, 2024 (the “Purchase Right”). The Purchase Right may be exercised early by the Minority Owners. The agreement to purchase the remaining interest was determined to be a financing due to the mandatory Purchase Right, as per ASC Topic 480, Distinguishing Liabilities From Equity , and as such, the Company recognized a liability for the remaining 40% interest. The Minority Owners exercised the Option, and on April 8, 2021, the Company completed the purchase of an additional 8% of the outstanding equity in Frontier for approximately $1,490. As a result, the Company’s ownership position in Frontier increased to 68%. Additionally, the Company fully consolidates Frontier as a VIE under ASC Topic No. 810, Consolidation . The following provides a summary of Frontier’s balance sheet as of December 31, 2021 and September 30, 2021, and summarized financial information for the three months ended December 31, 2021 and 2020. December 31, September 30, Current assets (includes cash of $4,790 and $2,095) $ 11,795 $ 12,495 Property, plant, and equipment 2,050 2,113 Goodwill 1,798 1,798 Intangible assets, net 7,852 8,265 Total liabilities (7,248) (9,425) Three Months Ended 2021 2020 Total revenue $ 6,949 $ 770 Total operating expenses (5,986) (1,738) Income (loss) from operations $ 963 $ (968)

Acquisitions

Acquisitions	3 Months Ended
	Dec. 31, 2021
Business Combinations [Abstract]
Acquisitions	AcquisitionsAcquisitions support the Company’s strategy of delivering a broad solutions portfolio with robust technology across multiple geographies and end markets. The Company continues to evaluate potential strategic acquisitions of businesses, assets and product lines and believes that capex-like, tuck-in acquisitions present a key opportunity within its overall growth strategy. On December 20, 2021, the Company and its indirect wholly-owned subsidiaries Evoqua Water Technologies LLC (“EWT LLC”) and Evoqua Water Technologies Ltd. (together with EWT LLC, the “Buyer”) entered into an Asset Purchase Agreement (the “Agreement”) with Cantel Medical LLC, Mar Cor Purification, Inc., and certain of their affiliates (collectively, the “Sellers”), each wholly-owned subsidiaries of Steris plc, pursuant to which the Buyer agreed to acquire certain assets of the Sellers and assume certain liabilities of the Sellers that are owned or used or arise in connection with the global operation of the Sellers’ renal business (the “Mar Cor Business”) for an aggregate purchase price of $196,300 in cash at closing (the “Purchase Price”), subject to customary adjustments, including for working capital (the “Transaction”). The Transaction closed on January 3, 2022. See Note 23, “Subsequent Events” for further discussion. We utilized cash on hand and borrowed an additional $160,000 under our 2021 Revolving Credit Facility (as defined below) to fund the transaction.The Purchase Price includes a $12,300 earn out, which is being held in escrow and will be paid, pro rata, to the Sellers if the Mar Cor Business meets certain sales performance goals (the “Earn Out”). Any portion of the Earn Out not paid to the Sellers during the first year following closing of the Transaction will be returned to the Buyer. In addition, approximately $12,965 of the Purchase Price was placed into an escrow account, of which $9,815 is to secure general indemnification claims against the Sellers and $3,150 is for net working capital adjustments. During the three months ended December 31, 2021, the Company incurred approximately $1,062 in acquisition costs, which are included in General and administrative expense on the Unaudited Consolidated Statements of Operations.

Revenue

Revenue	3 Months Ended
	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue Performance Obligations The Company elects to apply the practical expedient to exclude from this disclosure revenue related to performance obligations if the product has an alternative use and the Company does not have an enforceable right to payment for the performance completed to date, including a normal profit margin, in the event of termination for convenience. The Company maintains a backlog of confirmed orders, which totaled approximately $263,098 at December 31, 2021. This backlog represents the aggregate amount of the transaction price allocated to performance obligations that were unsatisfied or partially unsatisfied as of the end of the reporting period. The Company estimates that the majority of these performance obligations will be satisfied within the next twelve Disaggregation of Revenue In accordance with Topic 606, the Company disaggregates revenue from contracts with customers into source of revenue, reportable operating segment, and geographical regions. The Company determined that disaggregating revenue into these categories meets the disclosure objective in Topic 606, which is to depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. Information regarding the source of revenue: Three Months Ended 2021 2020 Revenue from contracts with customers recognized under Topic 606 $ 317,771 $ 285,188 Other (1) 48,497 37,005 Total $ 366,268 $ 322,193 (1) Other revenue relates to revenue recognized pursuant to ASU 2016-02, Leases (Topic 842) , primarily attributable to long term rentals. Information regarding revenue disaggregated by source of revenue and segment is as follows: Three Months Ended December 31, 2021 2020 Integrated Solutions and Services Revenue from capital projects $ 67,102 $ 50,626 Revenue from aftermarket 29,298 27,146 Revenue from service 148,646 136,945 Total $ 245,046 $ 214,717 Applied Product Technologies Revenue from capital projects $ 83,884 $ 76,889 Revenue from aftermarket 32,284 25,354 Revenue from service 5,054 5,233 Total $ 121,222 $ 107,476 Total Revenue Revenue from capital projects $ 150,986 $ 127,515 Revenue from aftermarket 61,582 52,500 Revenue from service 153,700 142,178 Total $ 366,268 $ 322,193 Information regarding revenue disaggregated by geographic area is as follows: Three Months Ended 2021 2020 United States $ 294,708 $ 264,131 Asia 30,905 22,605 Europe 25,629 21,285 Canada 12,661 11,179 Australia 2,365 2,993 Total $ 366,268 $ 322,193 Contract Balances The Company performs its obligations under a contract with a customer by transferring products and/or services in exchange for consideration from the customer. The Company receives payments from customers based on a billing schedule as established in its contracts. Contract assets relate to costs incurred to perform in advance of scheduled billings. Contract liabilities relate to payments received in advance of performance under the contracts. Change in contract assets and liabilities are due to the Company’s performance under the contract. The tables below provide a roll-forward of contract assets and contract liabilities balances for the periods presented: Three Months Ended Contract assets (a) 2021 2020 Balance at beginning of period $ 72,746 $ 80,759 Recognized in current period 120,387 66,885 Reclassified to accounts receivable (108,684) (88,560) Foreign currency 533 741 Balance at end of period $ 84,982 $ 59,825 (a) Excludes receivable balances which are disclosed on the Consolidated Balance Sheets. Three Months Ended Contract Liabilities 2021 2020 Balance at beginning of period $ 55,883 $ 26,259 Recognized in current period 100,017 96,230 Amounts in beginning balance reclassified to revenue (43,266) (24,895) Current period amounts reclassified to revenue (59,653) (62,730) Foreign currency 41 (419) Balance at end of period $ 53,022 $ 34,445

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurements As of December 31, 2021 and September 30, 2021, the fair values of cash and cash equivalents, accounts receivable, and accounts payable approximated carrying values due to the short maturity of these items. The Company measures the fair value of pension plan assets and liabilities, deferred compensation plan assets and liabilities on a recurring basis pursuant to ASC Topic No. 820, Fair Value Measurement . ASC Topic No. 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 plan 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 plan 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 measure the fair value of 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 December 31, 2021 Assets: Pension plan Cash $ — $ 756 $ — $ — Global Multi-Asset Fund 15,093 — — — Government Securities 2,494 — — — Liability Driven Investment 6,201 — — — Guernsey Unit Trust 2,493 — — — Global Absolute Return 2,221 — — — Deferred compensation plan assets Cash — 1,235 — — Mutual Funds — 17,769 — — Total return swaps—deferred compensation — — 55 — Interest rate swaps — — 9,469 — Foreign currency forward contracts — — 19 — Commodity swaps — — 1 — Liabilities: Pension plan — — (45,394) — Deferred compensation plan liabilities — — (25,331) — Long‑term debt — — (738,585) — Interest rate swaps — — (156) — Foreign currency forward contracts — — (29) — Earn-outs related to acquisitions — — — (50) Purchase Right — — — (8,305) Net Asset Value Quoted Market Significant Other Significant As of September 30, 2021 Assets: Pension plan Cash $ — $ 831 $ — $ — Global Multi-Asset Fund 15,244 — — — Government Securities 5,158 — — — Liability Driven Investment 2,793 — — — Guernsey Unit Trust 2,387 — — — Global Absolute Return 2,225 — — — Deferred compensation plan assets Cash — 1,251 — — Mutual Funds — 17,806 — — Interest rate swaps — — 3,127 — Foreign currency forward contracts — — 24 — Liabilities: Pension plan — — (46,013) — Deferred compensation plan liabilities — — (24,382) — Total return swaps—deferred compensation — — (130) — Long‑term debt — — (752,988) — Interest rate swaps — — (303) — Foreign currency forward contracts — — (102) — Commodity swaps — — (19) — Earn-outs related to acquisitions — — — (150) Purchase Right — — — (8,305) The pension plan assets and liabilities and deferred compensation plan assets and liabilities are included in Other non‑current assets and Other non‑current liabilities at December 31, 2021 and September 30, 2021. The unrealized gain on mutual funds was $641 at December 31, 2021. The Company records contingent consideration arrangements at fair value on a recurring basis, and the associated balances presented as of December 31, 2021 and September 30, 2021 are earn-outs related to acquisitions. The fair value of earn-outs related to acquisitions is based on significant unobservable inputs including the achievement of certain performance metrics. Significant changes in these inputs would result in corresponding increases or decreases in the fair value of the earn-out each period until the related contingency has been resolved. Changes in the fair value of the contingent consideration obligations can result from adjustments in the probability of achieving future development steps, sales targets and profitability and are recorded in General and administrative expenses in the Unaudited Consolidated Statements of Operations. During the three months ended December 31, 2021, the Company recorded a decrease in the fair value of the earn-out liability related to the prior year acquisition of Water Consulting Specialists, Inc. (“WCSI”) for $100. As of December 31, 2021 and September 30, 2021, earn-outs related to acquisitions totaled $50 and $150, respectively, and are included in Accrued expenses and other liabilities on the Consolidated Balance Sheets. The Company has a liability recorded for the Purchase Right to purchase the remaining 32% interest of Frontier. The fair value of this right is based upon significant unobservable inputs including future earnings and other market factors. Significant changes in these inputs would result in corresponding increases or decreases in the fair value of this right each period until the purchase of the remaining interest has occurred. Changes in the fair value can result from earnings

Accounts Receivable

Accounts Receivable	3 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Accounts receivable	Accounts Receivable Accounts receivable are summarized as follows: December 31, September 30, Accounts receivable $ 242,699 $ 282,819 Allowance for credit losses (5,776) (4,824) Receivables, net $ 236,923 $ 277,995 The movement in the allowance for credit losses was as follows for the three months ended December 31, 2021: Balance at September 30, 2021 $ (4,824) Charged to costs and expenses (852) Write-offs 30 Foreign currency and other (130) Balance at December 31, 2021 $ (5,776)

Inventories

Inventories	3 Months Ended
	Dec. 31, 2021
Inventory Disclosure [Abstract]
Inventories	Inventories The major classes of Inventories, net are as follows: December 31, September 30, Raw materials and supplies $ 93,271 $ 86,469 Work in progress 23,669 19,842 Finished goods and products held for resale 64,094 59,624 Costs of unbilled projects 2,887 2,277 Reserves for excess and obsolete (9,650) (9,709) Inventories, net $ 174,271 $ 158,503

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant, and Equipment Property, plant, and equipment consists of the following: December 31, September 30, Machinery and equipment $ 388,303 $ 388,352 Rental equipment 237,604 246,257 Land and buildings 69,522 70,048 Construction in process 64,310 59,737 759,739 764,394 Less: accumulated depreciation (386,666) (389,406) Property, plant, and equipment, net $ 373,073 $ 374,988 The Company entered into secured financing agreements that require providing a security interest in specified equipment. As of December 31, 2021 and September 30, 2021, the gross and net amounts of those assets are as follows: December 31, September 30, Gross Net Gross Net Machinery and equipment $ 73,749 $ 55,641 $ 73,632 $ 57,036 Construction in process 22,164 22,164 30,504 30,504 $ 95,913 $ 77,805 $ 104,136 $ 87,540 Depreciation expense and maintenance and repairs expense for the three months ended December 31, 2021 and 2020 were as follows: Three Months Ended 2021 2020 Depreciation expense $ 19,320 $ 18,511 Maintenance and repair expense 6,119 5,208

Goodwill

Goodwill	3 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Changes in the carrying amount of goodwill are as follows: Integrated Solutions and Services Applied Product Technologies Total Balance at September 30, 2021 $ 233,830 $ 173,546 $ 407,376 Foreign currency translation 222 (77) 145 Balance at December 31, 2021 $ 234,052 $ 173,469 $ 407,521 As of December 31, 2021 and September 30, 2021, $159,645 and $159,730, respectively, of goodwill was deductible for tax purposes.

Debt

Debt	3 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt Long‑term debt, including accrued interest, consists of the following: December 31, September 30, 2021 Term Loan, due April 1, 2028 (1) $ 472,650 $ 473,837 2021 Revolving Credit Facility, due April 1, 2026 (2) 27,269 37,268 Securitization Facility, due April 1, 2024 (3) 144,168 150,061 Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% 97,081 93,375 Notes Payable, due July 31, 2023 347 402 Total debt 741,515 754,943 Less unamortized deferred financing fees (11,272) (11,738) Total net debt 730,243 743,205 Less current portion (13,296) (12,775) Total long‑term debt $ 716,947 $ 730,430 (1) The interest rate on the 2021 Term Loan was 2.63% as of December 31, 2021, comprised of 0.13% LIBOR plus the 2.50% spread. Includes accrued interest of $25 at both December 31, 2021 and September 30, 2021. (2) The interest rate on the 2021 Revolving Credit Facility was 2.33% as of December 31, 2021, comprised of 0.13% LIBOR plus the 2.20% spread. During the three months ended December 31, 2021, the spread on the 2021 Revolving Credit Facility was reduced from 2.25% at September 30, 2021 as a result of a Sustainability Pricing Adjustment per the 2021 Credit Agreement. Includes accrued interest of $269 and $268, at December 31, 2021 and September 30, 2021, respectively. (3) The interest rate on the Securitization Facility was 1.35% as of December 31, 2021, comprised of 0.10% LIBOR plus the 1.25% spread. Includes accrued interest of $68 and $61 at December 31, 2021 and September 30, 2021, respectively. 2021 Credit Agreement On April 1, 2021, EWT III entered into a Credit Agreement (the “2021 Credit Agreement”) among EWT III, as borrower, EWT II, as parent guarantor, the lenders from time to time party thereto, JPMorgan Chase Bank, N.A., as administrative agent and collateral agent, and ING Capital, LLC, as sustainability coordinator. The 2021 Credit Agreement provides for a multi-currency senior secured revolving credit facility in an aggregate principal amount not to exceed the U.S. dollar equivalent of $350,000 (the “2021 Revolving Credit Facility”) and a discounted senior secured term (the “2021 Term Loan”) in the amount of $475,000 (together with the 2021 Revolving Credit Facility, the “Senior Facilities”). The 2021 Credit Agreement also provides for a letter of credit sub-facility not to exceed $60,000. The 2021 Credit Agreement contains customary representations, warranties, affirmative covenants, and negative covenants, including, among other things, a springing maximum first lien leverage ratio of 5.55 to 1.00. The Company did not exceed this ratio during the three months ended December 31, 2021, does not anticipate exceeding this ratio during the year ending September 30, 2022, and therefore does not anticipate any additional repayments during the year ending September 30, 2022. The following table summarizes the amount of the Company’s outstanding borrowings and outstanding letters of credit under the 2021 Revolving Credit Facility as of December 31, 2021 and September 30, 2021. December 31, September 30, Borrowing availability $ 350,000 $ 350,000 Outstanding borrowings 27,000 37,000 Outstanding letters of credit 9,828 10,112 Unused amounts $ 313,172 $ 302,888 Receivables Securitization Program On April 1, 2021, Evoqua Finance LLC (“Evoqua Finance”), an indirect wholly-owned subsidiary of the Company, entered into an accounts receivable securitization program (the “Receivables Securitization Program”) consisting of, among other agreements, (i) a Receivables Financing Agreement (the “Receivables Financing Agreement”) among Evoqua Finance, as the borrower, the lenders from time to time party thereto (the “Receivables Financing Lenders”), PNC Bank, National Association (“PNC Bank”), as administrative agent, EWT LLC, as initial servicer, and PNC Capital Markets LLC (“PNC Markets”), as structuring agent, pursuant to which the lenders have made available to Evoqua Finance a receivables finance facility (the “Securitization Facility”) in an amount up to $150,000 and (ii) a Sale and Contribution Agreement (the “Sale Agreement”) among Evoqua Finance, as purchaser, EWT LLC, as initial servicer and as an originator, and Neptune Benson, Inc., an indirectly wholly-owned subsidiary of the Company, as an originator (together with EWT LLC, the “Originators”). The Receivables Securitization Program contains certain customary representations, warranties, affirmative covenants, and negative covenants, subject to certain cure periods in some cases, including the eligibility of the Receivables being sold by the Originators and securing the loans made by the Receivables Financing Lenders, as well as customary reserve requirements, events of default, termination events, and servicer defaults. The Company was in compliance with all covenants during the three months ended December 31, 2021, does not anticipate becoming noncompliant during the year ending September 30, 2022, and therefore does not anticipate any additional repayments during the year ending September 30, 2022. Equipment Financings During the three months ended December 31, 2021, the Company completed the following equipment financings: Date Entered Due Interest Rate at 12/31/2021 Principal Amount December 30, 2021 December 30, 2028 3.94 % $ 2,207 December 23, 2021 July 31, 2029 (1) 4.75 % 3,742 $ 5,949 (1) Represents an advance received from the lender on a multiple draw term loan in which the Company is making interest only payments through August 1, 2022 based on a 1.00% LIBOR floor plus a 3.75% spread. The Company entered into an interest rate swap with an effective date of August 1, 2022 to mitigate risk associated with this variable rate equipment financing, see Note 12, “Derivative Financial Instruments” for further discussion. Deferred Financing Fees and Discounts Deferred financing fees and discounts related to the Company’s long-term debt were included as a contra liability to debt on the Consolidated Balance Sheets as follows: December 31, September 30, Current portion of deferred financing fees and discounts (1) $ (1,876) $ (1,866) Long-term portion of deferred financing fees and discounts (2) (9,396) (9,872) Total deferred financing fees and discounts $ (11,272) $ (11,738) (1) Included in Current portion of debt, net of deferred financing fees and discounts on the Consolidated Balance Sheets. (2) Included in Long-term debt, net of deferred financing fees and discounts on the Consolidated Balance Sheets. Amortization of deferred financing fees and discounts included in interest expense was $467 and $526 for the three months ended December 31, 2021 and 2020, respectively. Repayment Schedule Aggregate maturities of all long‑term debt, including current portion of long‑term debt and excluding finance lease obligations as of December 31, 2021, are presented below: Fiscal Year Remainder of 2022 $ 11,236 2023 16,062 2024 158,712 2025 16,162 2026 19,438 Thereafter 519,905 Total $ 741,515

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivative Financial Instruments Interest Rate Risk Management The Company is subject to market risk exposure arising from changes in interest rates on the senior secured credit facilities as well as variable rate equipment financings, which bear interest at rates that are indexed against LIBOR. The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to mitigate its exposure to rising interest rates. As of December 31, 2021, the notional amount of the Company’s interest rate swaps was $531,000. Foreign Currency Risk Management The Company’s functional currency is the U.S. dollar. By operating internationally, the Company is subject to foreign currency translation risk associated with converting the foreign operations’ financial statements into U.S. dollars transactions denominated in currencies other than the U.S. dollar (“foreign currencies”). The Company is also subject to currency risk from transactions denominated in foreign currencies. To mitigate cross-currency transaction risk, the Company analyzes significant exposures where it has receipts or payments in a currency other than the functional currency of its operations, and from time to time may strategically enter into short-term foreign currency forward contracts to lock in some or all of the cash flows associated with these transactions. The Company uses foreign currency derivative contracts in order to manage the effect of exchange fluctuations on forecasted sales and purchases that are denominated in foreign currencies. To mitigate the impact of foreign exchange rate risk, the Company entered into a series of forward contracts designated as cash flow hedges. As of December 31, 2021, the notional amount of the forward contracts was $5,494. Equity Price Risk Management The Company is exposed to variability in compensation charges related to certain deferred compensation obligations to employees. Equity price movements affect the compensation expense as certain investments made by the Company’s employees in the deferred compensation plan are revalued. Although not designated as accounting hedges, the Company utilizes derivatives such as total return swaps to economically hedge this exposure and offset the related compensation expense. As of December 31, 2021, the notional amount of the total return swaps was $6,519. Credit Risk Management The counterparties to the Company’s derivative contracts are highly-rated financial institutions. The Company regularly reviews the creditworthiness of its financial counterparties and fully expects the counterparties to perform under their respective agreements. The Company is not subject to any obligations to post collateral under derivative instrument contracts. The Company records all derivative instruments on a gross basis in the Consolidated Balance Sheets. Accordingly, there are no offsetting amounts that net assets against liabilities. Derivatives Designated as Cash Flow Hedges The following represents the fair value recorded for derivatives designated as cash flow hedges for the periods presented: Asset Derivatives Balance Sheet Location December 31, September 30, Interest rate swaps Prepaid and other current assets $ 9,469 $ 3,127 Foreign currency forward contracts Prepaid and other current assets 5 6 Commodity swaps Prepaid and other current assets 1 — Liability Derivatives Balance Sheet Location December 31, September 30, Interest rate swaps Accrued expenses and other current liabilities $ 156 $ 303 Foreign currency forward contracts Accrued expenses and other current liabilities 29 102 Commodity swaps Accrued expenses and other current liabilities — 19 The following represents the amount of gain (loss) recognized in Accumulated other comprehensive income (loss) (“AOCI”) (net of tax) during the periods presented: Three Months Ended 2021 2020 Interest rate swaps $ 5,871 $ 457 Foreign currency forward contracts (18) 3 Commodity swaps 20 — $ 5,873 $ 460 The following represents the amount of (loss) gain reclassified from AOCI into earnings during the periods presented: Three Months Ended Location of (Loss) Gain 2021 2020 Cost of product sales and services $ (85) $ — General and administrative expense (7) (32) Selling and marketing expense 1 — Interest expense (617) (510) $ (708) $ (542) Based on the fair value amounts of the Company’s cash flow hedges at December 31, 2021, the Company expects that approximately $4 of pre-tax net losses will be reclassified from AOCI into earnings during the next twelve months. The amount ultimately realized, however, will differ as exchange rates vary and the underlying contracts settle. Derivatives Not Designated as Hedging Instruments The following represents the fair value recorded for derivatives not designated as cash flow hedges for the periods presented: Asset Derivatives Balance Sheet Location December 31, September 30, Total return swaps—deferred compensation Prepaid and other current assets $ 55 $ — Foreign currency forward contracts Prepaid and other current assets 14 18 Liability Derivatives Balance Sheet Location December 31, September 30, Total return swaps—deferred compensation Accrued expenses and other current liabilities $ — $ 130 The following represents the amount of gain recognized in earnings for derivatives not designated as hedges during the periods presented: Three Months Ended Location of Gain 2021 2020 General and administrative expense $ 311 $ — $ 311 $ —

Product Warranties

Product Warranties	3 Months Ended
	Dec. 31, 2021
Guarantees and Product Warranties [Abstract]
Product warranties	Product Warranties A reconciliation of the activity related to the accrued warranty, including both the current and long‑term portions, is as follows: Current Product Warranties Non-Current Product Warranties Three Months Ended Three Months Ended 2021 2020 2021 2020 Balance at beginning of the period $ 8,138 $ 6,115 $ 2,966 $ 1,724 Warranty provision for sales 1,188 371 201 252 Settlement of warranty claims (1,262) (978) (219) (374) Foreign currency translation and other (171) 69 (46) 44 Balance at end of the period $ 7,893 $ 5,577 $ 2,902 $ 1,646

Restructuring and Related Charg

Restructuring and Related Charges	3 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Restructuring and related charges	Restructuring and Related Charges To better align its resources with its growth strategies and reduce its cost structure, the Company commits to various restructuring plans as necessary. The Company has undertaken various restructuring initiatives, including undertaking activities to reduce the cost structure and rationalize location footprint following the sale of the Memcor product line, transitioning from a three-segment structure to a two-segment operating model designed to better serve the needs of customers worldwide, and various initiatives within the Integrated Solutions and Services segment to drive efficiency and effectiveness in certain divisions. The Company currently expects to incur in future periods approximately $600 to $2,000 of costs related to restructuring programs initiated in prior periods. The table below sets forth the amounts accrued for the restructuring components and related activity: Three Months Ended 2021 2020 Balance at beginning of the period $ 304 $ 970 Restructuring charges following the sale of the Memcor product line 207 908 Restructuring charges related to two-segment realignment 164 238 Restructuring charges related to other initiatives 766 29 Release of prior reserves (21) (9) Write off charges — (121) Cash payments (1,138) (986) Other adjustments — 92 Balance at end of the period $ 282 $ 1,121 The balances for accrued restructuring liabilities at December 31, 2021 and September 30, 2021, are recorded in Accrued expenses and other liabilities on the Consolidated Balance Sheets. Restructuring charges primarily represent severance charges and other employee costs, fixed asset write-offs, and certain relocation expenses. The Company expects to pay the remaining amounts accrued as of December 31, 2021 during the remainder of fiscal 2022. The table below sets forth the location of amounts recorded above on the Unaudited Consolidated Statements of Operations: Three Months Ended 2021 2020 Cost of product sales and services $ 222 $ 826 General and administrative expense 894 138 Sales and marketing expense — 218 Research and development expense — (16) $ 1,116 $ 1,166

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Dec. 31, 2021
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 Siemens 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. The components of net periodic benefit cost for the plans were as follows: Three Months Ended 2021 2020 Service cost $ 232 $ 284 Interest cost 108 79 Expected return on plan assets (132) (87) Amortization of actuarial losses 169 264 Pension expense for defined benefit plans $ 377 $ 540 The components of pension expense, other than the service cost component which is included in General and administrative expense, are included in the line item Other operating expense in the Unaudited Consolidated Statements of Operations.

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Year-to-date income tax expense (benefit) is the product of the most current projected annual effective tax rate (“PAETR”) and the actual year-to-date pretax income (loss) adjusted for any discrete tax items. The income tax expense (benefit) for a particular quarter, except for the first quarter, is the difference between the year-to-date calculation of income tax expense (benefit) and the year-to-date calculation for the prior quarter. Items unrelated to current period ordinary income or (loss) are recognized entirely in the period identified as a discrete item of tax. Annual Effective Tax Rate The PAETR, which excludes the impact of discrete items, was 23.1% and 13.8% as of the three months ended December 31, 2021 and 2020, respectively. For the three months ended December 31, 2021, the PAETR was higher than the U.S. federal statutory rate of 21.0% primarily due to the mix of earnings between countries, most of which have higher statutory rates than the U.S., which was mostly offset by the impact of maintaining a valuation allowance that is provided on U.S. deferred tax assets. The current year PAETR was higher than the prior year’s rate due to an increase in projected pretax book income in countries with higher statutory tax rates. The Company continues to maintain a full valuation allowance 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 period ending December 31, 2021 as a result of pretax losses incurred since the Company’s inception in early 2014. The Company believes it is prudent to retain a valuation allowance until a more consistent pattern of earnings is established and net operating loss carryforwards begin to be utilized. Current and Prior Period Tax Expense For the three months ended December 31, 2021, the Company recognized income tax expense of $1,621 on pretax income of $7,709. The rate of 21.0% was in line with the U.S. statutory rate of 21.0% as the mix of earnings between countries, most of which have higher statutory tax rates than the U.S., was mostly offset by the impact of maintaining a U.S. valuation allowance that is provided on U.S. deferred tax assets. For the three months ended December 31, 2020, the Company recognized income tax expense of $1,084 on pretax income of $7,561. The rate of 14.3% differed from the U.S. statutory rate of 21.0% principally due to the impact of maintaining a U.S. valuation allowance against U.S. deferred tax assets.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Share Based Compensation	Share-Based CompensationThe Company designs equity compensation plans to attract and retain employees while also aligning employees’ interests with the interests of the Company’s shareholders. In addition, members of the Company’s Board of Directors (the “Board”) participate in equity compensation plans in connection with their service on the Board. The Company established the Evoqua Water Technologies Corp. Stock Option Plan (the “Stock Option Plan”) on March 6, 2014 . The plan allows certain management employees and the Board to purchase shares in the Company. Under the Stock Option Plan, the number of shares available for award was 11,083. As of December 31, 2021, there were approximately 2,177 shares available for future grants, however, the Company does not currently intend to make additional grants under the Stock Option Plan. In connection with the IPO, the Board adopted, and the Company’s shareholders approved, the Evoqua Water Technologies Corp. 2017 Equity Incentive Plan (the “Equity Incentive Plan”), under which equity 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). On December 31, 2021 (the “Grant Date”), the Company granted 219 restricted stock units and 98 performance share units (measured at a target award level) under the Equity Incentive Plan to certain employees of the Company. The final number of performance share units that may be earned is dependent on the Company’s achievement of performance goals related to organic revenue growth and adjusted EBITDA margin over a three-year measurement period ending September 30, 2024. The final number of performance share units that may be earned is also subject to a total stockholder return (“TSR”) modifier, which operates by increasing or decreasing the total number of shares earned by up to 25% based on the Company’s TSR relative to the TSR of the U.S. constituents of the S&P Global Water Index. In order to receive shares earned at the end of each performance period, the recipient must remain employed by the company at the end of the three-year period (except in the event of retirement, death, disability or, in certain circumstances, related to change in control). As of December 31, 2021, there were approximately 4,016 shares available for grants under the Equity Incentive Plan. Outstanding option awards vest ratably at 25% per year, and are exercisable at the time of vesting. The options granted have a ten A summary of the stock option activity as of December 31, 2021 is presented below: (In thousands, except per share amounts) Options Weighted Average Exercise Price/Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2021 5,090 $ 13.87 5.9 years $ 120,611 Granted 2 46.75 Exercised (64) 12.49 Forfeited (18) 20.29 Outstanding at December 31, 2021 5,010 $ 13.87 5.7 years $ 164,726 Options exercisable at December 31, 2021 3,126 $ 9.67 4.3 years $ 115,912 Options vested and expected to vest at December 31, 2021 4,992 $ 13.84 5.7 years $ 164,312 The total intrinsic value of options exercised (which is the amount by which the stock price exceeded the exercise price of the options on the date of exercise) during the three months ended December 31, 2021 was $1,949. A summary of the status of the Company's unvested stock options as of and for the three months ended December 31, 2021 is presented below. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Unvested at beginning of period 1,901 $ 6.69 Granted 2 24.22 Vested (1) 8.12 Forfeited (18) 6.47 Unvested at end of period 1,884 $ 6.73 The total fair value of options vested during the three months ended December 31, 2021, was $4. The following is a summary of the restricted stock units (“RSU”) activity for the three months ended December 31, 2021. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Outstanding at September 30, 2021 1,209 $ 22.77 Granted 261 45.81 Vested (115) 24.48 Forfeited (16) 23.03 Outstanding at December 31, 2021 1,339 $ 27.11 Expected to vest at December 31, 2021 1,292 $ 26.75 The following is a summary of the performance share unit activity for the three months ended December 31, 2021, assuming target award level. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Unvested at beginning of period 469 $ 16.92 Granted 98 52.57 Unvested at end of period 567 $ 23.10 Expected to vest 518 $ 23.01 Expense Measurement and Recognition The Company recognizes share-based compensation for all currently outstanding awards and, in future periods, will recognize compensation costs for the unvested portion of awards based on grant date fair values. Total share-based compensation expense was $5,334 and $3,076 during the three months ended December 31, 2021 and 2020, respectively, of which $5,203 and $3,019 was non-cash, respectively. The unrecognized compensation expense related to stock options, RSUs, and performance share units (measured at a target award level) was $7,501, $28,941 and $11,444, respectively at December 31, 2021, and is expected to be recognized over a weighted average period of 1.8 years, 2.2 years and 2.5 years, respectively. The Company received $2,085 from the exercise of stock options during the three months ended December 31, 2021. Employee Stock Purchase Plan Effective October 1, 2018, the Company implemented an employee stock purchase plan (the “ESPP”) which allows employees to purchase shares of the Company’s stock at 85% of the lower of the fair market value on the first day of the applicable offering period or on the last business day of a six

Concentration of Credit Risk

Concentration of Credit Risk	3 Months Ended
	Dec. 31, 2021
Risks and Uncertainties [Abstract]
Concentration of credit risk	Concentration of Credit RiskThe 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 December 31, 2021 and September 30, 2021 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 three months ended December 31, 2021 and 2020, no customer accounted for more than 10% of net sales or net accounts receivable.The Company operates predominantly in ten 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 Integrated Solutions and Services and Applied Product Technologies segments. The Company is a multi-national business but its sales and operations are primarily in the U.S. Sales to unaffiliated customers are transacted with the Company location that maintains the customer relationship.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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. The following summarizes the Company’s outstanding letters of credit and surety bonds as of December 31, 2021 and September 30, 2021, respectively. December 31, September 30, Revolving credit capacity $ 60,000 $ 60,000 Letters of credit outstanding 9,828 10,112 Remaining revolving credit capacity $ 50,172 $ 49,888 Surety capacity $ 250,000 $ 250,000 Surety issuances 142,709 147,845 Remaining surety available $ 107,291 $ 102,155 The longest maturity date of letters of credit and surety bonds in effect as of December 31, 2021 was March 20, 2030. Litigation 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 is commenced against it arising from or related to: product liability; personal injury; trademarks, trade secrets, or other intellectual property; shareholder disputes; 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 its results of operations, or financial condition.

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	3 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following: December 31, September 30, Salaries, wages, and other benefits $ 62,154 $ 79,110 Obligation under operating leases 13,066 13,316 Obligation under finance leases 12,124 12,093 Third party commissions 10,274 10,031 Taxes, other than income 4,941 4,575 Insurance liabilities 3,845 3,720 Provisions for litigation 3,078 2,938 Severance payments 282 304 Fair value of liability derivatives 185 554 Earn-outs related to acquisitions 50 150 Other 34,445 33,576 $ 144,444 $ 160,367

Business Segments

Business Segments	3 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Business segments	Business SegmentsThe Company’s reportable operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated on a regular basis by the chief operating decision maker, or decision making group, in deciding how to allocate resources to an individual segment and in assessing performance. The key factors used to identify these reportable operating segments are the organization and alignment of the Company’s internal operations, the nature of the products and services, and customer type. The Company has two reportable operating segments, Integrated Solutions and Services and Applied Product Technologies. The business segments are described as follows: Integrated Solutions and Services is a group entirely focused on engaging directly with end users through direct sales with a market vertical focus. Integrated Solutions and Services provides tailored services and solutions in collaboration with the customers backed by life‑cycle services including on‑demand water, outsourced water, recycle / reuse, and emergency response service alternatives to improve operational reliability, performance, and environmental compliance. Key offerings within this segment also include equipment systems for industrial needs (influent water, boiler feed water, ultrahigh purity, process water, wastewater treatment, and recycle / reuse), full-scale outsourcing of operations and maintenance, and municipal services, including odor and corrosion control services. Applied Product Technologies is focused on developing product platforms to be sold primarily through third party channels. This segment primarily engages in indirect sales through independent sales representatives, distributors, and aftermarket channels. Applied Product Technologies provides a range of highly differentiated and scalable products and technologies specified by global water treatment designers, original equipment manufacturers (“OEMs”), engineering firms, and integrators. Key offerings within this segment include filtration and separation, disinfection, wastewater solutions, anode and electrochlorination technology, and aquatics technologies and solutions for the global recreational and commercial pool market. Corporate activities include general corporate expenses, elimination of inter-segment transactions, interest income and expense, and certain other charges. Certain other charges may include 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 and certain integration costs,), and share-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. Reportable operating segment revenue and operating profit for the three months ended December 31, 2021 and 2020 were as follows: Three Months Ended 2021 2020 Total revenue Integrated Solutions and Services $ 253,576 $ 216,753 Applied Product Technologies 142,497 123,581 Total revenue 396,073 340,334 Intersegment revenue Integrated Solutions and Services 8,530 2,036 Applied Product Technologies 21,275 16,105 Total intersegment revenue 29,805 18,141 Revenue to external customers Integrated Solutions and Services 245,046 214,717 Applied Product Technologies 121,222 107,476 Total revenue $ 366,268 $ 322,193 Operating profit (loss) Integrated Solutions and Services $ 35,300 $ 26,357 Applied Product Technologies 17,827 13,380 Corporate (38,839) (23,503) Total operating profit 14,288 16,234 Interest expense (6,579) (8,673) Income before income taxes 7,709 7,561 Income tax expense (1,621) (1,084) Net income $ 6,088 $ 6,477

Earnings per Share

Earnings per Share	3 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Earnings per share	Earnings Per Share The following table sets forth the computation of basic and diluted earnings from continuing operations per common share (in thousands, except per share amounts): Three Months Ended 2021 2020 Numerator: Numerator for basic and diluted earnings per common share—Net income attributable to Evoqua Water Technologies Corp. $ 5,987 $ 6,433 Denominator: Denominator for basic net income per common share—weighted average shares 120,632 117,768 Effect of dilutive securities: Share‑based compensation 4,315 3,790 Denominator for diluted net income per common share—adjusted weighted average shares 124,947 121,558 Basic earnings attributable to Evoqua Water Technologies Corp. per common share $ 0.05 $ 0.05 Diluted earnings attributable to Evoqua Water Technologies Corp. per common share $ 0.05 $ 0.05

Subsequent Events

Subsequent Events	3 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 3, 2022, the Company completed the Transaction to acquire the Mar Cor Business for $194,977 paid in cash at closing. The Company utilized cash on hand and borrowed an additional $160,000 under its 2021 Revolving Credit Facility to fund the Transaction. On January 18, 2022, the Company paid $2,300 for a success fee to a third party, which was due upon consummation of the Transaction. The Mar Cor Business is a leading manufacturer and servicer of medical water, commercial and industrial solutions in North America. Headquartered in Plymouth, Minnesota, the Mar Cor Business has 27 service and regeneration facilities in the U.S. and Canada. The Mar Cor Business offers significant technical expertise in designing, building, and servicing high-purity water treatment systems. In connection with the closing of the Transaction, EWT LLC entered into contract manufacturing agreements with the Sellers pursuant to which the Sellers will manufacture certain filtration and dialysis concentrates products for EWT LLC.

Organization, Consolidation and

Organization, Consolidation and Presentation of Financial Statements (Policies)	3 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of Presentation The accompanying Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”). All intercompany transactions have been eliminated. Unless otherwise specified, all dollar and share amounts in these notes are referred to in thousands. The interim Unaudited 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. In our opinion, all adjustments considered necessary for a fair presentation of the financial statements have been included, and all adjustments are of a normal and recurring nature. We consistently applied the accounting policies described in our Annual Report on Form 10-K for the fiscal year ended September 30, 2021, as filed with the SEC on November 17, 2021 (“2021 Annual Report”), in preparing these Unaudited Consolidated Financial Statements, with the exception of accounting standard updates described in Note 2, “Recent Accounting Pronouncements.” These Unaudited Consolidated Financial Statements should be read in conjunction with the audited financial statements and the notes included in our 2021 Annual Report. Certain prior period amounts have been reclassified to conform to the current period presentation.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Recent accounting pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Not Yet Adopted In October 2021, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , which amends Accounting Standards Codification (“ASC”) 805 to require an acquirer to, at the date of acquisition, recognize and measure contract assets and contract liabilities acquired in accordance with ASU 2014-9, Revenue from Contracts with Customers (Topic 606) (“Topic 606”) , as if the entity had originated the contracts, rather than adjust them to fair value at the acquisition date. The guidance is effective for fiscal years beginning after December 15, 2022 and is to be applied prospectively to business combinations occurring on or after the effective date of the amendments. The Company is currently assessing the impact of adoption on the Company’s Unaudited Consolidated Financial Statements and related disclosures. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , and also issued subsequent amendments to the initial guidance (collectively, “Topic 848”). Topic 848 became effective immediately and expires on December 31, 2022. Topic 848 allows eligible contracts that are modified to be accounted for as a continuation of those contracts, permits companies to preserve their hedge accounting during the transition period and enables companies to make a one-time election to transfer or sell held-to-maturity debt securities that are affected by rate reform. Topic 848 provides optional expedients and exceptions for contracts, hedging relationships and other transactions that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform if certain criteria are met. The Company is currently assessing the impact of adoption on the Company’s Unaudited Consolidated Financial Statements and related disclosures.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Information regarding the source of revenue: Three Months Ended 2021 2020 Revenue from contracts with customers recognized under Topic 606 $ 317,771 $ 285,188 Other (1) 48,497 37,005 Total $ 366,268 $ 322,193 (1) Other revenue relates to revenue recognized pursuant to ASU 2016-02, Leases (Topic 842) , primarily attributable to long term rentals. Information regarding revenue disaggregated by source of revenue and segment is as follows: Three Months Ended December 31, 2021 2020 Integrated Solutions and Services Revenue from capital projects $ 67,102 $ 50,626 Revenue from aftermarket 29,298 27,146 Revenue from service 148,646 136,945 Total $ 245,046 $ 214,717 Applied Product Technologies Revenue from capital projects $ 83,884 $ 76,889 Revenue from aftermarket 32,284 25,354 Revenue from service 5,054 5,233 Total $ 121,222 $ 107,476 Total Revenue Revenue from capital projects $ 150,986 $ 127,515 Revenue from aftermarket 61,582 52,500 Revenue from service 153,700 142,178 Total $ 366,268 $ 322,193 Information regarding revenue disaggregated by geographic area is as follows: Three Months Ended 2021 2020 United States $ 294,708 $ 264,131 Asia 30,905 22,605 Europe 25,629 21,285 Canada 12,661 11,179 Australia 2,365 2,993 Total $ 366,268 $ 322,193
Contract with Customer, Asset and Liability	The tables below provide a roll-forward of contract assets and contract liabilities balances for the periods presented: Three Months Ended Contract assets (a) 2021 2020 Balance at beginning of period $ 72,746 $ 80,759 Recognized in current period 120,387 66,885 Reclassified to accounts receivable (108,684) (88,560) Foreign currency 533 741 Balance at end of period $ 84,982 $ 59,825 (a) Excludes receivable balances which are disclosed on the Consolidated Balance Sheets. Three Months Ended Contract Liabilities 2021 2020 Balance at beginning of period $ 55,883 $ 26,259 Recognized in current period 100,017 96,230 Amounts in beginning balance reclassified to revenue (43,266) (24,895) Current period amounts reclassified to revenue (59,653) (62,730) Foreign currency 41 (419) Balance at end of period $ 53,022 $ 34,445

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2021
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 plan 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 plan 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 measure the fair value of 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 December 31, 2021 Assets: Pension plan Cash $ — $ 756 $ — $ — Global Multi-Asset Fund 15,093 — — — Government Securities 2,494 — — — Liability Driven Investment 6,201 — — — Guernsey Unit Trust 2,493 — — — Global Absolute Return 2,221 — — — Deferred compensation plan assets Cash — 1,235 — — Mutual Funds — 17,769 — — Total return swaps—deferred compensation — — 55 — Interest rate swaps — — 9,469 — Foreign currency forward contracts — — 19 — Commodity swaps — — 1 — Liabilities: Pension plan — — (45,394) — Deferred compensation plan liabilities — — (25,331) — Long‑term debt — — (738,585) — Interest rate swaps — — (156) — Foreign currency forward contracts — — (29) — Earn-outs related to acquisitions — — — (50) Purchase Right — — — (8,305) Net Asset Value Quoted Market Significant Other Significant As of September 30, 2021 Assets: Pension plan Cash $ — $ 831 $ — $ — Global Multi-Asset Fund 15,244 — — — Government Securities 5,158 — — — Liability Driven Investment 2,793 — — — Guernsey Unit Trust 2,387 — — — Global Absolute Return 2,225 — — — Deferred compensation plan assets Cash — 1,251 — — Mutual Funds — 17,806 — — Interest rate swaps — — 3,127 — Foreign currency forward contracts — — 24 — Liabilities: Pension plan — — (46,013) — Deferred compensation plan liabilities — — (24,382) — Total return swaps—deferred compensation — — (130) — Long‑term debt — — (752,988) — Interest rate swaps — — (303) — Foreign currency forward contracts — — (102) — Commodity swaps — — (19) — Earn-outs related to acquisitions — — — (150) Purchase Right — — — (8,305)

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Schedule of accounts receivable	Accounts receivable are summarized as follows: December 31, September 30, Accounts receivable $ 242,699 $ 282,819 Allowance for credit losses (5,776) (4,824) Receivables, net $ 236,923 $ 277,995
Accounts Receivable, Allowance for Credit Loss	The movement in the allowance for credit losses was as follows for the three months ended December 31, 2021: Balance at September 30, 2021 $ (4,824) Charged to costs and expenses (852) Write-offs 30 Foreign currency and other (130) Balance at December 31, 2021 $ (5,776)

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Dec. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory	The major classes of Inventories, net are as follows: December 31, September 30, Raw materials and supplies $ 93,271 $ 86,469 Work in progress 23,669 19,842 Finished goods and products held for resale 64,094 59,624 Costs of unbilled projects 2,887 2,277 Reserves for excess and obsolete (9,650) (9,709) Inventories, net $ 174,271 $ 158,503

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	3 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, plant, and equipment consists of the following: December 31, September 30, Machinery and equipment $ 388,303 $ 388,352 Rental equipment 237,604 246,257 Land and buildings 69,522 70,048 Construction in process 64,310 59,737 759,739 764,394 Less: accumulated depreciation (386,666) (389,406) Property, plant, and equipment, net $ 373,073 $ 374,988 Depreciation expense and maintenance and repairs expense for the three months ended December 31, 2021 and 2020 were as follows: Three Months Ended 2021 2020 Depreciation expense $ 19,320 $ 18,511 Maintenance and repair expense 6,119 5,208
Schedule of Financial Instruments Owned and Pledged as Collateral	December 31, September 30, Gross Net Gross Net Machinery and equipment $ 73,749 $ 55,641 $ 73,632 $ 57,036 Construction in process 22,164 22,164 30,504 30,504 $ 95,913 $ 77,805 $ 104,136 $ 87,540

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of goodwill are as follows: Integrated Solutions and Services Applied Product Technologies Total Balance at September 30, 2021 $ 233,830 $ 173,546 $ 407,376 Foreign currency translation 222 (77) 145 Balance at December 31, 2021 $ 234,052 $ 173,469 $ 407,521

Debt (Tables)

Debt (Tables)	3 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long‑term debt, including accrued interest, consists of the following: December 31, September 30, 2021 Term Loan, due April 1, 2028 (1) $ 472,650 $ 473,837 2021 Revolving Credit Facility, due April 1, 2026 (2) 27,269 37,268 Securitization Facility, due April 1, 2024 (3) 144,168 150,061 Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% 97,081 93,375 Notes Payable, due July 31, 2023 347 402 Total debt 741,515 754,943 Less unamortized deferred financing fees (11,272) (11,738) Total net debt 730,243 743,205 Less current portion (13,296) (12,775) Total long‑term debt $ 716,947 $ 730,430 (1) The interest rate on the 2021 Term Loan was 2.63% as of December 31, 2021, comprised of 0.13% LIBOR plus the 2.50% spread. Includes accrued interest of $25 at both December 31, 2021 and September 30, 2021. (2) The interest rate on the 2021 Revolving Credit Facility was 2.33% as of December 31, 2021, comprised of 0.13% LIBOR plus the 2.20% spread. During the three months ended December 31, 2021, the spread on the 2021 Revolving Credit Facility was reduced from 2.25% at September 30, 2021 as a result of a Sustainability Pricing Adjustment per the 2021 Credit Agreement. Includes accrued interest of $269 and $268, at December 31, 2021 and September 30, 2021, respectively. (3) The interest rate on the Securitization Facility was 1.35% as of December 31, 2021, comprised of 0.10% LIBOR plus the 1.25% spread. Includes accrued interest of $68 and $61 at December 31, 2021 and September 30, 2021, respectively.
Schedule of Line of Credit Facilities	The following table summarizes the amount of the Company’s outstanding borrowings and outstanding letters of credit under the 2021 Revolving Credit Facility as of December 31, 2021 and September 30, 2021. December 31, September 30, Borrowing availability $ 350,000 $ 350,000 Outstanding borrowings 27,000 37,000 Outstanding letters of credit 9,828 10,112 Unused amounts $ 313,172 $ 302,888 The following summarizes the Company’s outstanding letters of credit and surety bonds as of December 31, 2021 and September 30, 2021, respectively. December 31, September 30, Revolving credit capacity $ 60,000 $ 60,000 Letters of credit outstanding 9,828 10,112 Remaining revolving credit capacity $ 50,172 $ 49,888 Surety capacity $ 250,000 $ 250,000 Surety issuances 142,709 147,845 Remaining surety available $ 107,291 $ 102,155
Schedule of Equipment Financing	During the three months ended December 31, 2021, the Company completed the following equipment financings: Date Entered Due Interest Rate at 12/31/2021 Principal Amount December 30, 2021 December 30, 2028 3.94 % $ 2,207 December 23, 2021 July 31, 2029 (1) 4.75 % 3,742 $ 5,949
Schedule of Deferred Financing Costs and Discounts	Deferred financing fees and discounts related to the Company’s long-term debt were included as a contra liability to debt on the Consolidated Balance Sheets as follows: December 31, September 30, Current portion of deferred financing fees and discounts (1) $ (1,876) $ (1,866) Long-term portion of deferred financing fees and discounts (2) (9,396) (9,872) Total deferred financing fees and discounts $ (11,272) $ (11,738) (1) Included in Current portion of debt, net of deferred financing fees and discounts on the Consolidated Balance Sheets.
Schedule of Aggregate Maturities of Long-term Debt	Aggregate maturities of all long‑term debt, including current portion of long‑term debt and excluding finance lease obligations as of December 31, 2021, are presented below: Fiscal Year Remainder of 2022 $ 11,236 2023 16,062 2024 158,712 2025 16,162 2026 19,438 Thereafter 519,905 Total $ 741,515

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	3 Months Ended
	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following represents the fair value recorded for derivatives designated as cash flow hedges for the periods presented: Asset Derivatives Balance Sheet Location December 31, September 30, Interest rate swaps Prepaid and other current assets $ 9,469 $ 3,127 Foreign currency forward contracts Prepaid and other current assets 5 6 Commodity swaps Prepaid and other current assets 1 — Liability Derivatives Balance Sheet Location December 31, September 30, Interest rate swaps Accrued expenses and other current liabilities $ 156 $ 303 Foreign currency forward contracts Accrued expenses and other current liabilities 29 102 Commodity swaps Accrued expenses and other current liabilities — 19 The following represents the fair value recorded for derivatives not designated as cash flow hedges for the periods presented: Asset Derivatives Balance Sheet Location December 31, September 30, Total return swaps—deferred compensation Prepaid and other current assets $ 55 $ — Foreign currency forward contracts Prepaid and other current assets 14 18 Liability Derivatives Balance Sheet Location December 31, September 30, Total return swaps—deferred compensation Accrued expenses and other current liabilities $ — $ 130
Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)	The following represents the amount of gain (loss) recognized in Accumulated other comprehensive income (loss) (“AOCI”) (net of tax) during the periods presented: Three Months Ended 2021 2020 Interest rate swaps $ 5,871 $ 457 Foreign currency forward contracts (18) 3 Commodity swaps 20 — $ 5,873 $ 460
Derivative Instruments, Gain (Loss)	The following represents the amount of (loss) gain reclassified from AOCI into earnings during the periods presented: Three Months Ended Location of (Loss) Gain 2021 2020 Cost of product sales and services $ (85) $ — General and administrative expense (7) (32) Selling and marketing expense 1 — Interest expense (617) (510) $ (708) $ (542)
Derivatives Not Designated as Hedging Instruments	The following represents the amount of gain recognized in earnings for derivatives not designated as hedges during the periods presented: Three Months Ended Location of Gain 2021 2020 General and administrative expense $ 311 $ — $ 311 $ —

Product Warranties (Tables)

Product Warranties (Tables)	3 Months Ended
	Dec. 31, 2021
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: Current Product Warranties Non-Current Product Warranties Three Months Ended Three Months Ended 2021 2020 2021 2020 Balance at beginning of the period $ 8,138 $ 6,115 $ 2,966 $ 1,724 Warranty provision for sales 1,188 371 201 252 Settlement of warranty claims (1,262) (978) (219) (374) Foreign currency translation and other (171) 69 (46) 44 Balance at end of the period $ 7,893 $ 5,577 $ 2,902 $ 1,646

Restructuring and Related Cha_2

Restructuring and Related Charges (Tables)	3 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Schedule of restructuring components	Three Months Ended 2021 2020 Balance at beginning of the period $ 304 $ 970 Restructuring charges following the sale of the Memcor product line 207 908 Restructuring charges related to two-segment realignment 164 238 Restructuring charges related to other initiatives 766 29 Release of prior reserves (21) (9) Write off charges — (121) Cash payments (1,138) (986) Other adjustments — 92 Balance at end of the period $ 282 $ 1,121 The table below sets forth the location of amounts recorded above on the Unaudited Consolidated Statements of Operations: Three Months Ended 2021 2020 Cost of product sales and services $ 222 $ 826 General and administrative expense 894 138 Sales and marketing expense — 218 Research and development expense — (16) $ 1,116 $ 1,166

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Schedule of net benefit costs	The components of net periodic benefit cost for the plans were as follows: Three Months Ended 2021 2020 Service cost $ 232 $ 284 Interest cost 108 79 Expected return on plan assets (132) (87) Amortization of actuarial losses 169 264 Pension expense for defined benefit plans $ 377 $ 540

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock options, activity	A summary of the stock option activity as of December 31, 2021 is presented below: (In thousands, except per share amounts) Options Weighted Average Exercise Price/Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2021 5,090 $ 13.87 5.9 years $ 120,611 Granted 2 46.75 Exercised (64) 12.49 Forfeited (18) 20.29 Outstanding at December 31, 2021 5,010 $ 13.87 5.7 years $ 164,726 Options exercisable at December 31, 2021 3,126 $ 9.67 4.3 years $ 115,912 Options vested and expected to vest at December 31, 2021 4,992 $ 13.84 5.7 years $ 164,312
Schedule of Nonvested Share Activity	A summary of the status of the Company's unvested stock options as of and for the three months ended December 31, 2021 is presented below. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Unvested at beginning of period 1,901 $ 6.69 Granted 2 24.22 Vested (1) 8.12 Forfeited (18) 6.47 Unvested at end of period 1,884 $ 6.73
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following is a summary of the restricted stock units (“RSU”) activity for the three months ended December 31, 2021. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Outstanding at September 30, 2021 1,209 $ 22.77 Granted 261 45.81 Vested (115) 24.48 Forfeited (16) 23.03 Outstanding at December 31, 2021 1,339 $ 27.11 Expected to vest at December 31, 2021 1,292 $ 26.75 The following is a summary of the performance share unit activity for the three months ended December 31, 2021, assuming target award level. (In thousands, except per share amounts) Shares Weighted Average Grant Date Fair Value/Share Unvested at beginning of period 469 $ 16.92 Granted 98 52.57 Unvested at end of period 567 $ 23.10 Expected to vest 518 $ 23.01

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Line of Credit Facilities	The following table summarizes the amount of the Company’s outstanding borrowings and outstanding letters of credit under the 2021 Revolving Credit Facility as of December 31, 2021 and September 30, 2021. December 31, September 30, Borrowing availability $ 350,000 $ 350,000 Outstanding borrowings 27,000 37,000 Outstanding letters of credit 9,828 10,112 Unused amounts $ 313,172 $ 302,888 The following summarizes the Company’s outstanding letters of credit and surety bonds as of December 31, 2021 and September 30, 2021, respectively. December 31, September 30, Revolving credit capacity $ 60,000 $ 60,000 Letters of credit outstanding 9,828 10,112 Remaining revolving credit capacity $ 50,172 $ 49,888 Surety capacity $ 250,000 $ 250,000 Surety issuances 142,709 147,845 Remaining surety available $ 107,291 $ 102,155

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	3 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued expenses and other liabilities consisted of the following: December 31, September 30, Salaries, wages, and other benefits $ 62,154 $ 79,110 Obligation under operating leases 13,066 13,316 Obligation under finance leases 12,124 12,093 Third party commissions 10,274 10,031 Taxes, other than income 4,941 4,575 Insurance liabilities 3,845 3,720 Provisions for litigation 3,078 2,938 Severance payments 282 304 Fair value of liability derivatives 185 554 Earn-outs related to acquisitions 50 150 Other 34,445 33,576 $ 144,444 $ 160,367

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	Three Months Ended 2021 2020 Total revenue Integrated Solutions and Services $ 253,576 $ 216,753 Applied Product Technologies 142,497 123,581 Total revenue 396,073 340,334 Intersegment revenue Integrated Solutions and Services 8,530 2,036 Applied Product Technologies 21,275 16,105 Total intersegment revenue 29,805 18,141 Revenue to external customers Integrated Solutions and Services 245,046 214,717 Applied Product Technologies 121,222 107,476 Total revenue $ 366,268 $ 322,193 Operating profit (loss) Integrated Solutions and Services $ 35,300 $ 26,357 Applied Product Technologies 17,827 13,380 Corporate (38,839) (23,503) Total operating profit 14,288 16,234 Interest expense (6,579) (8,673) Income before income taxes 7,709 7,561 Income tax expense (1,621) (1,084) Net income $ 6,088 $ 6,477

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	The following table sets forth the computation of basic and diluted earnings from continuing operations per common share (in thousands, except per share amounts): Three Months Ended 2021 2020 Numerator: Numerator for basic and diluted earnings per common share—Net income attributable to Evoqua Water Technologies Corp. $ 5,987 $ 6,433 Denominator: Denominator for basic net income per common share—weighted average shares 120,632 117,768 Effect of dilutive securities: Share‑based compensation 4,315 3,790 Denominator for diluted net income per common share—adjusted weighted average shares 124,947 121,558 Basic earnings attributable to Evoqua Water Technologies Corp. per common share $ 0.05 $ 0.05 Diluted earnings attributable to Evoqua Water Technologies Corp. per common share $ 0.05 $ 0.05

Description of the Company an_2

Description of the Company and Basis of Presentation (Details) $ in Thousands	Oct. 29, 2018segment	Dec. 31, 2021USD ($)segment	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Subsidiary, Sale of Stock [Line Items]
Number of reportable segments | segment	3	2
Net cash provided by operating activities		$ 36,380		$ 23,269
Net cash provided by financing activities		15,879		$ (4,619)
Classification Error | Additional Paid-in Capital
Subsidiary, Sale of Stock [Line Items]
Classification error between additional paid in capital and accumulated other comprehensive balances			$ 18,669
Classification Error | Accumulated Other Comprehensive (Loss) Income
Subsidiary, Sale of Stock [Line Items]
Classification error between additional paid in capital and accumulated other comprehensive balances			18,669
Revision of Prior Period, Error Correction, Adjustment | Classification Error
Subsidiary, Sale of Stock [Line Items]
Net cash provided by operating activities			7,655
Net cash provided by financing activities			$ 7,655
Revision of Prior Period, Error Correction, Adjustment | Understatement
Subsidiary, Sale of Stock [Line Items]
Net cash provided by operating activities		7,655
Revision of Prior Period, Error Correction, Adjustment | Overstatement
Subsidiary, Sale of Stock [Line Items]
Net cash provided by financing activities		$ 7,655

Investments, Equity Method and

Investments, Equity Method and Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2021	Apr. 08, 2021	Feb. 28, 2021	Oct. 01, 2019
Schedule of Equity Method Investments [Line Items]
Obligation to absorb risk of loss, percentage of partner's equity	100.00%
Current assets	$ 681,902			$ 678,458
Property, plant, and equipment, net	373,073			374,988
Goodwill	407,521			407,376
Other non‑current assets	72,082			64,188
Liabilities	(1,265,008)			(1,286,672)
Operating Expenses	(97,730)		$ (79,334)
Operating profit (loss)	14,288		16,234
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Schedule of Equity Method Investments [Line Items]
Purchase of outstanding equity	$ 8,305			8,305
Frontier
Schedule of Equity Method Investments [Line Items]
Percentage of voting interests acquired	68.00%				8.00%		60.00%
Remaining percentage to be acquired	40.00%						3200.00%
Purchase of additional interest in subsidiaries		$ 1,490
Frontier | Maximum
Schedule of Equity Method Investments [Line Items]
Remaining percentage to be acquired						10.00%
Treated Water Outsourcing
Schedule of Equity Method Investments [Line Items]
Partnership interest	50.00%
Current assets	$ 3,272			3,202
Property, plant, and equipment, net	842			903
Goodwill	2,206			2,206
Liabilities	(1,017)			(1,009)
Cash	1,363			1,380
Revenues	845		834
Operating Expenses	(737)		(737)
Operating profit (loss)	108		97
Frontier
Schedule of Equity Method Investments [Line Items]
Current assets	11,795			12,495
Property, plant, and equipment, net	2,050			2,113
Goodwill	1,798			1,798
Other non‑current assets	7,852			8,265
Liabilities	(7,248)			(9,425)
Cash	4,790			$ 2,095
Revenues	6,949		770
Operating Expenses	(5,986)		(1,738)
Operating profit (loss)	$ 963		$ (968)

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Mar Cor | Subsequent Event
Business Acquisition [Line Items]
Asset acquisition, purchase price expected	$ 196,300
Contingent consideration, liability	$ 12,300
Mar Cor
Business Acquisition [Line Items]
Effective date of acquisition		Dec. 20, 2021
Acquisition costs		$ 1,062
Mar Cor | Subsequent Event
Business Acquisition [Line Items]
Effective date of acquisition	Jan. 3, 2022
Borrowings under credit facility	$ 160,000
Escrow Deposit	12,965
Mar Cor | General Indemnity | Subsequent Event
Business Acquisition [Line Items]
Escrow Deposit	9,815
Mar Cor | Working Capital Adjustments | Subsequent Event
Business Acquisition [Line Items]
Escrow Deposit	$ 3,150

Revenue (Performance Obligation

Revenue (Performance Obligation) (Details) $ in Thousands	Dec. 31, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 263,098
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period: 2021-01-01 | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period: 2021-01-01 | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	24 months

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		$ 366,268	$ 322,193
Other	[1]	48,497	37,005
United States
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		294,708	264,131
Europe
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		25,629	21,285
Asia
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		30,905	22,605
Canada
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		12,661	11,179
Australia
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		2,365	2,993
Integrated Solutions and Services
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		245,046	214,717
Applied Product Technologies
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		121,222	107,476
Revenue from aftermarket
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		61,582	52,500
Revenue from aftermarket | Integrated Solutions and Services
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		29,298	27,146
Revenue from aftermarket | Applied Product Technologies
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		32,284	25,354
Revenue from service
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		153,700	142,178
Revenue from service | Integrated Solutions and Services
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		148,646	136,945
Revenue from service | Applied Product Technologies
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		5,054	5,233
Revenue from capital projects
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		150,986	127,515
Revenue from capital projects | Integrated Solutions and Services
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		67,102	50,626
Revenue from capital projects | Applied Product Technologies
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		83,884	76,889
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Revenue from product sales and services		$ 317,771	$ 285,188
[1]	Other revenue relates to revenue recognized pursuant to ASU 2016-02, Leases (Topic 842) , primarily attributable to long term rentals.

Revenue (Contract Assets and Li

Revenue (Contract Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Contract liabilities	$ 53,022	$ 34,445	$ 55,883	$ 26,259
Change in Contract with Customer, Asset [Roll Forward]
beginning of period	72,746	80,759
Recognized in current period	120,387	66,885
Reclassified to accounts receivable	108,684	88,560
Foreign currency	533	741
end of period	84,982	59,825
Change in Contract with Customer, Liability [Roll Forward]
Recognized in current period	100,017	96,230
Amounts in beginning balance reclassified to revenue	(43,266)	(24,895)
Current period amounts reclassified to revenue	(59,653)	(62,730)
Foreign currency	$ 41	$ (419)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Deferred compensation plan assets
Mutual Funds	$ 17,769
Fair Value, Measurements, Recurring | Quoted Market Prices in Active Markets (Level 1)
Deferred compensation plan assets
Cash	1,235	$ 1,251
Mutual Funds		17,806
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets:
Foreign currency forward contracts	19	24
Deferred compensation plan assets
Mutual Funds		0
Interest rate cap		3,127
Liabilities:
Pension plan	(45,394)	(46,013)
Deferred compensation plan liabilities	(25,331)	(24,382)
Total Return Swaps, Fair Value	(55)	130
Long‑term debt	(738,585)	(752,988)
Interest Rate Derivative Liabilities, at Fair Value	(156)	(303)
Foreign currency forward contracts	(29)	(102)
Commodity Swaps, Fair Value Disclosure	(1)	19
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Other Current Liabilities | Designated as Hedging Instrument
Deferred compensation plan assets
Interest rate cap	9,469
Liabilities:
Interest Rate Derivative Liabilities, at Fair Value	(156)	(303)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Liabilities:
Earn-outs related to acquisitions	(50)	(150)
Option and purchase right	(8,305)	(8,305)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Other Current Liabilities
Liabilities:
Earn-outs related to acquisitions	(50)	(50)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Other Noncurrent Liabilities
Liabilities:
Option and purchase right	(8,305)
Fair Value, Measurements, Recurring | Cash | Quoted Market Prices in Active Markets (Level 1)
Assets:
Defined benefit plan, fair value of plan assets	756	831
Fair Value, Measurements, Recurring | US Government Agencies Debt Securities
Assets:
Plan assets at net asset value	2,494	5,158
Fair Value, Measurements, Recurring | Liability Driven Investment
Assets:
Plan assets at net asset value	6,201	2,793
Fair Value, Measurements, Recurring | Guernsey Unit Trust
Assets:
Plan assets at net asset value	2,493	2,387
Fair Value, Measurements, Recurring | Global Absolute Return
Assets:
Plan assets at net asset value	2,221	2,225
Fair Value, Measurements, Recurring | Hedge Funds, Multi-strategy
Assets:
Plan assets at net asset value	$ 15,093	$ 15,244

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Oct. 01, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unrealized Gain (Loss) on Investments	$ 641
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Earn-out payments, change in fair value	(100)
Earn-out related to acquisitions	50	$ 150
Option and purchase right	8,305	8,305
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other Current Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Earn-out related to acquisitions	50	$ 50
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other Noncurrent Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Option and purchase right	$ 8,305
Frontier
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Remaining percentage to be acquired	40.00%		3200.00%

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Sep. 30, 2021
Receivables [Abstract]
Accounts receivable	$ 242,699	$ 282,819
Allowance for credit losses	(5,776)	(4,824)
Accounts receivable, net	236,923	$ 277,995
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at September 30, 2020	(4,824)
Charged to costs and expenses	(852)
Write-offs	30
Foreign currency and other	(130)
Balance at December 31, 2020	$ (5,776)

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 93,271	$ 86,469
Work in progress	23,669	19,842
Finished goods and products held for resale	64,094	59,624
Costs of unbilled projects	2,887	2,277
Reserves for excess and obsolete	(9,650)	(9,709)
Inventory, Net	$ 174,271	$ 158,503

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 759,739		$ 764,394
Less: accumulated depreciation	(386,666)		(389,406)
Property, plant, and equipment, net	373,073		374,988
Depreciation and amortization	19,320	$ 18,511
Maintenance and repair expense	6,119	$ 5,208
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	388,303		388,352
Land and buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	69,522		70,048
Construction in process
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	64,310		59,737
Rental equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 237,604		$ 246,257

Property, Plant, and Equipmen_3

Property, Plant, and Equipment Property, Plant and Equipment (Secured Financing Agreements) (Details) - Equipment Financings - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Property, plant and equipment gross [Member]
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	$ 95,913	$ 104,136
Property, plant and equipment gross [Member] | Machinery and equipment
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	73,749	73,632
Property, plant and equipment gross [Member] | Construction in process
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	22,164	30,504
Property, plant and equipment net [Member]
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	77,805	87,540
Property, plant and equipment net [Member] | Machinery and equipment
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	55,641	57,036
Property, plant and equipment net [Member] | Construction in process
Debt Instrument [Line Items]
Pledged Assets, Not Separately Reported, Other	$ 22,164	$ 30,504

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Business acquisition, goodwill, expected tax deductible, amount	$ 159,645	$ 159,730

Goodwill (Schedule of Goodwill)

Goodwill (Schedule of Goodwill) (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2021USD ($)
Goodwill [Roll Forward]
Goodwill, beginning of the period	$ 407,376
Foreign currency translation	145
Goodwill, end of the period	407,521
Operating Segments | Integrated Solutions and Services
Goodwill [Roll Forward]
Goodwill, beginning of the period	233,830
Foreign currency translation	222
Goodwill, end of the period	234,052
Operating Segments | Applied Product Technologies
Goodwill [Roll Forward]
Goodwill, beginning of the period	173,546
Foreign currency translation	(77)
Goodwill, end of the period	$ 173,469

Debt (Schedule of Long-term Deb

Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Total debt	$ 741,515	$ 754,943
Less unamortized deferred financing fees	(11,272)	(11,738)
Total net debt	730,243	743,205
Current portion of debt	(13,296)	(12,775)
Total long‑term debt	$ 716,947	730,430
Securitization Facility, due April 1, 2024
Debt Instrument [Line Items]
Debt , interest rate, effective percentage	1.35%
Debt instrument, basis spread on variable rate	1.25%
Securitization Facility, due April 1, 2024 | LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.10%
2021 Revolving Credit Facility, due April 2026
Debt Instrument [Line Items]
Total debt	$ 27,269	$ 37,268
Debt , interest rate, effective percentage	2.33%
Debt instrument, basis spread on variable rate	2.20%	2.25%
Interest payable	$ 269	$ 268
2021 Revolving Credit Facility, due April 2026 | LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.13%
Securitization Facility, due April 1, 2024
Debt Instrument [Line Items]
Total debt	$ 144,168	150,061
Interest payable	68	61
Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Total debt	97,081	93,375
Notes Payable, due July 31, 2023
Debt Instrument [Line Items]
Total debt	347	402
2021 Term Loan
Debt Instrument [Line Items]
Total debt	$ 472,650	$ 473,837
Debt , interest rate, effective percentage	2.63%
Debt instrument, basis spread on variable rate	2.50%
Interest payable	$ 25
2021 Term Loan | LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.13%
Minimum | Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.13%
Maximum | Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.07%

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Apr. 01, 2021
Line of Credit Facility [Line Items]
Amortization of debt issuance costs and discounts	$ 467,000	$ 526,000
Maximum
Line of Credit Facility [Line Items]
Accounts receivable from securitization			$ 150,000,000
2021 Credit Agreement | Term Loan
Line of Credit Facility [Line Items]
Amount of loan			475,000,000
Revolving Credit Facility | 2021 Credit Agreement
Line of Credit Facility [Line Items]
Credit facility borrowing capacity			350,000,000
Letter of Credit | 2021 Credit Agreement
Line of Credit Facility [Line Items]
Credit facility borrowing capacity			$ 60,000,000

Debt (Schedule of Line of Credi

Debt (Schedule of Line of Credit Facilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity	$ 60,000	$ 60,000
Debt instrument, unused borrowing capacity, amount	50,172	49,888
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity	350,000	350,000
Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	9,828	10,112
Debt instrument, unused borrowing capacity, amount	313,172	302,888
2021 Revolving Credit Facility, due April 2026
Line of Credit Facility [Line Items]
line of Credit Facility, Amount Drawn	$ 27,000	$ 37,000

Debt (Schedule of Equipment Fin

Debt (Schedule of Equipment Financings) (Details) - Loans Payable $ in Thousands	3 Months Ended
	Dec. 31, 2021USD ($)
Equipment Financing Due Dec 30 2028
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.0394%
Total debt	$ 2,207
Equipment Financing Due July 31 2029
Debt Instrument [Line Items]
Debt , interest rate, effective percentage	0.0475%
Total debt	$ 3,742
Debt instrument, basis spread on variable rate	3.75%
Equipment Financing Due July 31 2029 | LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Equipment Financings
Debt Instrument [Line Items]
Total debt	$ 5,949

Debt (schedule of Deferred Fina

Debt (schedule of Deferred Financing Fees and Discounts (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Unamortized discount (premium) and debt issuance costs, net	$ 11,272	$ 11,738
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Unamortized discount (premium) and debt issuance costs, net	(11,272)	(11,738)
First Lien Term Facility, due December 20, 2024 | Other Current Liabilities
Debt Instrument [Line Items]
Unamortized discount (premium) and debt issuance costs, net	(1,876)	(1,866)
First Lien Term Facility, due December 20, 2024 | Other Noncurrent Liabilities
Debt Instrument [Line Items]
Unamortized discount (premium) and debt issuance costs, net	$ (9,396)	$ (9,872)

Debt (Long-term Debt Maturities

Debt (Long-term Debt Maturities) (Details) $ in Thousands	Dec. 31, 2021USD ($)
Debt Disclosure [Abstract]
2022	$ 11,236
2023	16,062
2024	158,712
2025	16,162
2026	19,438
Thereafter	519,905
Long-term Debt	$ 741,515

Derivative Financial Instrume_3

Derivative Financial Instruments - Narrative (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2021USD ($)
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred	$ (4)
Description of Reclassification of Cash Flow Hedge Gain (Loss)	twelve months
Interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount	$ 531,000
Foreign currency forward contracts
Derivative [Line Items]
Derivative, Notional Amount	5,494
Commodity swaps
Derivative [Line Items]
Derivative, Notional Amount	$ 6,519

Derivative Financial Instrume_4

Derivative Financial Instruments (Fair Values) (Details) - Fair Value, Inputs, Level 2 - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Derivatives, Fair Value [Line Items]
Interest rate cap		$ 3,127
Interest Rate Derivative Liabilities, at Fair Value	$ 156	303
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets | Interest rate swaps
Derivatives, Fair Value [Line Items]
Interest rate cap	9,469	3,127
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Foreign Currency Cash Flow Hedge Asset at Fair Value	5	6
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets | Commodity swaps
Derivatives, Fair Value [Line Items]
Price Risk Derivative Assets, at Fair Value	1	0
Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Interest rate cap	9,469
Interest Rate Derivative Liabilities, at Fair Value	156	303
Foreign Currency Cash Flow Hedge Liability at Fair Value	29	102
Price Risk Fair Value Hedge Liability, at Fair Value	$ 0	$ 19

Derivative Financial Instrume_5

Derivative Financial Instruments (Amounts Recognized in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized derivative gain on cash flow hedges, net of tax	$ 6,581	$ 1,002
Other Comprehensive Income (Loss) | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized derivative gain on cash flow hedges, net of tax	5,873	460
Interest rate swaps | Other Comprehensive Income (Loss) | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized derivative gain on cash flow hedges, net of tax	5,871	457
Foreign currency forward contracts | Other Comprehensive Income (Loss) | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized derivative gain on cash flow hedges, net of tax	(18)	3
Commodity swaps | Other Comprehensive Income (Loss) | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized derivative gain on cash flow hedges, net of tax	$ 20	$ 0

Derivative Financial Instrume_6

Derivative Financial Instruments (Amounts Reclassified out of AOCI) (Details) - Reclassification out of Accumulated Other Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	$ (708)	$ (542)
Cost of Product Sales and Services
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	(85)	0
General and Administrative Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	(7)	(32)
Sales and Marketing Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	1	0
Interest Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	$ (617)	$ (510)

Derivative Financial Instrume_7

Derivative Financial Instruments (Derivatives Not Designated as Cash Flow Hedges) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Derivatives, Fair Value [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	$ 311	$ 0
General and Administrative Expense
Derivatives, Fair Value [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain	311	$ 0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Total Return Swap | Not Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	55		$ 0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Total Return Swap | Not Designated as Hedging Instrument | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	0		130
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Foreign currency forward contracts | Not Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 14		$ 18

Product Warranties (Details)

Product Warranties (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Balance at beginning of the period	$ 8,138
Balance at beginning of the period	2,966
Balance at end of the period	7,893
Balance at end of the period	2,902
Other Current Liabilities
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Balance at beginning of the period	8,138	$ 6,115
Warranty provision for sales	1,188	371
Settlement of warranty claims	(1,262)	(978)
Foreign currency translation and other	(171)	69
Balance at end of the period	7,893	5,577
Other Noncurrent Liabilities
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Balance at beginning of the period	2,966	1,724
Warranty provision for sales	201	252
Settlement of warranty claims	(219)	(374)
Foreign currency translation and other	(46)	44
Balance at end of the period	$ 2,902	$ 1,646

Restructuring and Related Cha_3

Restructuring and Related Charges (Details) $ in Thousands	Oct. 29, 2018segment	Dec. 31, 2021USD ($)segment	Dec. 31, 2020USD ($)
Restructuring Cost and Reserve [Line Items]
Number of reportable segments | segment	3	2
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of the period		$ 304	$ 970
Restructuring charges		1,116	1,166
Release of prior reserves		21	9
Write off charges		0	(121)
Cash payments		(1,138)	(986)
Other adjustments		0	92
Restructuring reserve, end of the period		282	1,121
Cost of Product Sales and Services
Restructuring Reserve [Roll Forward]
Restructuring charges		222	826
General and Administrative Expense
Restructuring Reserve [Roll Forward]
Restructuring charges		894	138
Sales and Marketing Expense
Restructuring Reserve [Roll Forward]
Restructuring charges		0	218
Research and Development Expense
Restructuring Reserve [Roll Forward]
Restructuring charges		0	(16)
Post Memcor product line sale restructuring
Restructuring Reserve [Roll Forward]
Restructuring charges		207	908
Two-segment realignment
Restructuring Reserve [Roll Forward]
Restructuring charges		164	238
Other Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charges		766	$ 29
Other Restructuring | Minimum
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost		600
Other Restructuring | Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost		$ 2,000

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Service cost	$ 232	$ 284
Interest cost	108	79
Expected return on plan assets	(132)	(87)
Amortization of actuarial losses	169	264
Pension expense for defined benefit plans	$ 377	$ 540

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Estimated Annual Effective Tax Rate Used to Calculate Income Tax Expense (Benefit)	23.10%	13.80%
Federal statutory income tax rate, percent	21.00%	21.00%
Income tax expense	$ (1,621)	$ (1,084)
Income before income taxes	$ 7,709	$ 7,561
Effective income tax rate reconciliation, percent	21.00%	14.30%
Unrecognized Tax Benefits	$ 1,628	$ 1,322

Share-Based Compensation (Detai

Share-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	May 18, 2021	Oct. 01, 2020	Dec. 21, 2018	Oct. 01, 2018	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)					2
Intrinsic value, exercises in period					$ 1,949
Fair value of options vested					4
Share-based Compensation expense					5,334	$ 3,076
Non-cash share-based compensation					5,203	3,019
Compensation cost not yet recognized, period for recognition					28,941
Proceeds from issuance of common stock					$ 2,085	6,617
Employee Stock Ownership Plan (ESOP), Shares in ESOP			11,297
Common stock, par value (in dollars per share)					$ 0.01		$ 0.01
Evoqua Water Technologies Corp. Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting percentage					25.00%
Contractual term of options					10 years
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan, number of shares authorized (shares)					11,083
Number of shares available for grant (in shares)					2,177
Compensation cost not yet recognized, period for recognition					$ 7,501
Period for recognition for unrecognized compensation expense					1 year 9 months 18 days
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)					4,016
Purchase price of stock, percentage				85.00%
Purchase period				6 months
Employee Stock Ownership Plan (ESOP), Shares in ESOP			5,000
Employee Stock Ownership Plan (ESOP), Compensation Expense					$ 221	$ 216
Shares issued under ESPP		60
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition for unrecognized compensation expense					2 years 2 months 12 days
Vested in period (shares)					115
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in dollars per share)			$ 0.01
Special RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)	219
Compensation cost not yet recognized, period for recognition					$ 11,444
Period for recognition for unrecognized compensation expense					2 years 6 months
Special PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)	98

Share-Based Compensation (Stock

Share-Based Compensation (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Options
Outstanding at beginning of the period (shares)	5,090,000
Granted (shares)	2,000
Exercised (shares)	(64,000)
Forfeited (shares)	(18,000)
Outstanding at end of the period (shares)	5,010,000
Options exercisable (shares)	3,126,000
Options vested and expected to vest (shares)	4,992,000
Weighted Average Exercise Price/Share
Weighted average exercise price, outstanding, beginning balance (in dollars per share)	$ 13.87
Weighted average exercise price, granted (in dollars per share)	46.75
Weighted average exercise price, exercised (in dollars per share)	12.49
Weighted average exercise price, forfeited (in dollars per share)	20.29
Weighted average exercise price, outstanding, ending balance (in dollars per share)	13.87
Weighted average exercise price, exercisable (in dollars per share)	9.67
Weighted average exercise price, options vested and expected to vest (in dollars per share)	$ 13.84
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term, outstanding	5 years 8 months 12 days	5 years 10 months 24 days
Weighted average contractual term, exercisable	4 years 3 months 18 days
Weighted average remaining contractual term, options vested and expected to vest	5 years 8 months 12 days
Intrinsic value, outstanding	$ 164,726		$ 120,611
Intrinsic value, exercisable	115,912
Intrinsic value, options vested and expected to vest	$ 164,312

Share-Based Compensation (Nonve

Share-Based Compensation (Nonvested Share Activity) (Details)	3 Months Ended
	Dec. 31, 2021$ / sharesshares
Shares
Unvested at beginning of period | shares	1,901,000
Granted (shares) | shares	2,000
Vested (shares) | shares	(1,000)
Forfeited (shares) | shares	(18,000)
Unvested at end of period | shares	1,884,000
Weighted Average Grant Date Fair Value/Share
Weighted average grant date fair value, nonvested, beginning balance (in dollars per share) | $ / shares	$ 6.69
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	24.22
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	8.12
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	6.47
Weighted average grant date fair value, nonvested, ending balance (in dollars per share) | $ / shares	$ 6.73

Share-Based Compensation (RSU A

Share-Based Compensation (RSU Activity) (Details) shares in Thousands	3 Months Ended
	Dec. 31, 2021$ / sharesshares
Shares
Forfeited | shares	18
Options exercisable (shares) | shares	3,126
Weighted Average Grant Date Fair Value/Share
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	$ 6.47
Weighted average exercise price, options vested and expected to vest (in dollars per share) | $ / shares	$ 13.84
Restricted Stock Units (RSUs)
Shares
Outstanding at beginning of the period (shares) | shares	1,209
Granted | shares	261
Vested in period (shares) | shares	(115)
Forfeited | shares	16
Outstanding at beginning of the period | shares	1,339
Options exercisable (shares) | shares	1,292
Weighted Average Grant Date Fair Value/Share
Weighted average grant date fair value, nonvested, equity instruments other than options, beginning of the period (in dollar per share) | $ / shares	$ 22.77
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	45.81
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	24.48
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	23.03
Weighted average grant date fair value, nonvested, equity instruments other than options, end of the period (in dollar per share) | $ / shares	27.11
Weighted average exercise price, options vested and expected to vest (in dollars per share) | $ / shares	$ 26.75
Special RSU
Shares
Outstanding at beginning of the period (shares) | shares	469
Granted | shares	98
Outstanding at beginning of the period | shares	567
Options exercisable (shares) | shares	518
Weighted Average Grant Date Fair Value/Share
Weighted average grant date fair value, nonvested, equity instruments other than options, beginning of the period (in dollar per share) | $ / shares	$ 16.92
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	52.57
Weighted average grant date fair value, nonvested, equity instruments other than options, end of the period (in dollar per share) | $ / shares	23.10
Weighted average exercise price, options vested and expected to vest (in dollars per share) | $ / shares	$ 23.01

Concentration of Credit Risk (D

Concentration of Credit Risk (Details)	Dec. 31, 2021country
Risks and Uncertainties [Abstract]
Number of countries in which entity operates	10

Commitments and Contingencies_2

Commitments and Contingencies (Schedule of Letters of Credit and Surety Bonds) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Sep. 30, 2021
Other Commitments [Line Items]
Revolving credit capacity	$ 60,000	$ 60,000
Remaining revolving credit capacity	50,172	49,888
Surety Bond
Other Commitments [Line Items]
Surety capacity	250,000	250,000
Surety issuances	142,709	147,845
Remaining surety available	$ 107,291	102,155
Minimum | Surety Bond
Other Commitments [Line Items]
Letter of Credit, Guarantee, Bond Commitments, Expiration Period	12 months
Maximum | Surety Bond
Other Commitments [Line Items]
Letter of Credit, Guarantee, Bond Commitments, Expiration Period	10 years
Letter of Credit
Other Commitments [Line Items]
Letters of credit outstanding, amount	$ 9,828	10,112
Remaining revolving credit capacity	$ 313,172	$ 302,888
Debt Instrument, Maturity Date	Mar. 20, 2030

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Payables and Accruals [Abstract]
Salaries, wages, and other benefits	$ 62,154	$ 79,110
Obligation under operating leases	13,066	13,316
Obligation under finance leases	12,124	12,093
Third party commissions	10,274	10,031
Taxes, other than income	4,941	4,575
Insurance liabilities	3,845	3,720
Provision for litigation	3,078	2,938
Severance payments	282	304
Fair value of liability derivatives	185	554
Earn-outs related to acquisitions	50	150
Other	34,445	33,576
Accrued expenses and other liabilities	$ 144,444	$ 160,367
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued expenses and other liabilities	Accrued expenses and other liabilities
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued expenses and other liabilities

Business Segments (Details)

Business Segments (Details) $ in Thousands	Oct. 29, 2018segment	Dec. 31, 2021USD ($)segment	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	3	2
Segment Reporting Information [Line Items]
Revenue from product sales and services		$ 366,268	$ 322,193
Operating profit (loss)		14,288	16,234
Interest expense		(6,579)	(8,673)
Income before income taxes		7,709	7,561
Income tax (expense) benefit		(1,621)	(1,084)
Net income		6,088	6,477
Assets		1,867,601		$ 1,868,891
Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services		245,046	214,717
Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services		121,222	107,476
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue from product sales and services		29,805	18,141
Intersegment Eliminations | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Revenue from product sales and services		8,530	2,036
Intersegment Eliminations | Applied Product Technologies
Segment Reporting Information [Line Items]
Revenue from product sales and services		21,275	16,105
Operating Segments
Segment Reporting Information [Line Items]
Total revenue		396,073	340,334
Operating Segments | Integrated Solutions and Services
Segment Reporting Information [Line Items]
Total revenue		253,576	216,753
Revenue from product sales and services		245,046
Operating profit (loss)		35,300	26,357
Assets		870,124		887,265
Operating Segments | Applied Product Technologies
Segment Reporting Information [Line Items]
Total revenue		142,497	123,581
Revenue from product sales and services		121,222
Operating profit (loss)		17,827	13,380
Assets		636,832		656,362
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Operating profit (loss)		(38,839)	$ (23,503)
Assets		$ 360,645		$ 325,264

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Numerator for basic and diluted earnings per common share—Net income attributable to Evoqua Water Technologies Corp.	$ 5,987	$ 6,433
Denominator:
Denominator for basic net income per common share—weighted average shares	120,632	117,768
Effect of dilutive securities:
Share‑based compensation	4,315	3,790
Denominator for diluted net income per common share—adjusted weighted average shares	124,947	121,558
Basic income per common share	$ 0.05	$ 0.05
Diluted income per common share	$ 0.05	$ 0.05

Subsequent Events (Details)

Subsequent Events (Details) - Mar Cor - USD ($) $ in Thousands	Jan. 18, 2022	Jan. 03, 2022	Mar. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Effective date of acquisition				Dec. 20, 2021
Subsequent Event
Subsequent Event [Line Items]
Payments to acquire businesses		$ 194,977
Effective date of acquisition			Jan. 3, 2022
Borrowings under credit facility			$ 160,000
Subsequent Event | Success Fee
Subsequent Event [Line Items]
Business Combination, Acquisition Related Costs	$ 2,300