[KRIEG DeVAULT ALEXANDER & CAPEHART LETTERHEAD]

     March 24, 1998

     Board of Directors                      Board of Directors
     Environmental Test Systems, Inc.        Hach Company
     23575 County Road 106                   5600 Lindbergh Drive
     Elkhart, Indiana  46514                 Loveland, Colorado 80538

          RE:  Merger of Environmental Test Systems, Inc. into Hach 
     Acquisition Corp.

     Ladies and Gentlemen:

          The respective Boards of Directors of Environmental Test Systems, 
     Inc. ("ETS") and Hach Company ("Hach") have requested our opinion as to 
     certain federal income tax consequences of a reorganization involving 
     Hach, Hach Acquisition Corp. ("Mergerco") and ETS.

           In summary, the proposed transaction involves the merger of ETS 
     with and into Mergerco ("Merger"), with Mergerco as the surviving entity 
     ("Surviving Entity").   In consideration of the proposed Merger, 
     non-dissenting ETS Class A Common Stock shareholders will receive Class 
     A Common Merger Consideration (as hereinafter defined) and cash for any 
     fractional share interest of Hach Common Stocks (as hereinafter defined) 
     to be received in the exchange and the non-dissenting ETS Class B Common 
     Stock shareholders will receive Class B Common Merger Consideration (as 
     hereinafter defined)  and cash for any fractional share interest of Hach 
     Common Stocks to be received in the exchange.  Upon and after 
     consummation of the proposed transaction, Mergerco will continue as a 
     wholly-owned subsidiary of Hach.  

                                        FACTS

          In connection with the Merger, the following facts have been 
     provided to us, and we have relied upon them for purposes of this 
     opinion:

          A.   HACH COMPANY

          Hach maintains its principal office at 5600 Lindbergh Drive, 
     Loveland, Colorado 80538.  Hach is a corporation duly incorporated and 
     existing under the laws of the State of Delaware.  As of March 2, 1998, 
     Hach had 25,000,000 shares of voting, $1.00 par value, common stock 
     authorized, of which approximately 8,257,897 shares were issued and 
     outstanding ("Hach Common Stock"), and 20,000,000 shares of voting, no 
     par value Class 



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 2

     A common stock, of which approximately 8,243,137 shares were issued and 
     outstanding ("Hach Class A Common Stock") (collectively, the Hach Common 
     Stock and the Hach Class A Common Stock are hereinafter referred to as 
     the "Hach Common Stocks").  The Hach Common Stocks are traded in the 
     over-the-counter market and stock prices are reported on the Nasdaq 
     National Market System. 

          The following table sets forth, as of March 2, 1998, the number and 
     percentage of outstanding shares beneficially owned by each person known 
     by Hach to own beneficially more than 5% of the outstanding shares of 
     the Hach Common Stocks, by each director and named executive officer of 
     Hach, and by all the directors and executive officers of Hack as a 
     group. 



             NAME                          HACH COMMON STOCK        HACH CLASS A COMMON STOCK
             ----                          -----------------        -------------------------
                                         Number of                   Number of              
                                          Shares        Percent        Shares            Percent
                                                                              
     Kathryn C. Hach-Darrow .......   4,573,891(1)(2)     54.46%    4,573,891(1)(2)       54.56

     Hach Company Employee Stock 
     Ownership Plan and Trust .....     702,762(3)         8.37       702,762(3)           8.38

     Bruce J. Hach ................     166,148(2)(4)(5)   1.98       166,148(2)(4)(5)     1.98

     Gary R. Dreher ...............      40,925(2)(4)(6)     *        166,148(2)(4)(6)     *

     Joseph V. Schwan .............      28,326(2)(4)        *         28,326(2)(4)        *

     Fred W. Wenninger ............      11,089(2)(4)        *         11,089(2)(4)        *

     John N. McConnell ............      18,545(2)(4)        *         19,423(2)(4)        *

     Linda O. Doty ................      19,432(2)(4)        *         19,423(2)(4)        *

     All current executive officers
     and directors as a group .....   5,037,467(2)(4)(7)  59.98     5,039,275(2)(4)(7)    60.11

     *    Less than 1%





Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 3


     (1)  The shares listed in the table above opposite Kathryn 
          Hach-Darrow's name include 927,281 shares held in Mrs. 
          Hack-Darrow's name.  The shares listed above also include 
          2,014,400 shares which are held in three trusts created by the 
          late Clifford C. Hach and which Mrs. Hack-Darrow has the power 
          as trustee to vote and dispose of, namely, Kathryn C. Hach 
          Marital Trust, the Clifford C. Hach Generation Skipping Trust, 
          and the Clifford C. Hach Family Trust, all three of which 
          Trusts were created under an agreement dated August 30, 1998, 
          by Clifford C. Hach.  Mrs. Hach-Darrow has the power to vote 
          and dispose of the shares held in the Marital, Generation 
          Skipping and Family Trusts.  In addition, the shares listed 
          above opposite Mrs. Hach-Darrow's name include 1,511,415 
          shares owned by C&K Enterprises, Ltd., as to which Mrs. 
          Hach-Darrow and the Kathryn C. Hach Marital Trust have voting 
          and investment powers, 120,782 shares owned by the Hach 
          Scientific Foundation, a charitable foundation, and 3 shares 
          allocated to Mrs. Hach-Darrow's account under the Employee 
          Stock Ownership Plan (the "Hach ESOP"). Mrs. Hach-Darrow is 
          President and a co-trustee of the Foundation and shares voting 
          and investment powers with respect to the shares  held by the 
          Foundation.  The business address of Mrs. Hach-Darrow is 5600 
          Lindbergh Drive, Loveland, Colorado  80537.

     (2)  Excludes 147,979 shares owned by the Hach Company 401(k) 
          Plan.  Hach through its board of directors has the power to 
          vote such shares.  In addition, the co-trustees of the 401(k) 
          Plan share investment power with respect to those shares.  
          Also excludes shares of the Hach ESOP, as to which the Company 
          through its Board of Directors, and the ESOP's co-trustees, 
          have investment power.  The co-trustees of each of the 401(k) 
          Plan and the ESOP are Randall A. Petersen, Gary R. Dreher and 
          Loel J. Sirovy.  The Hach ESOP as of March 2, 1998 held a 
          total of 702,762 shares, all of which were allocated to the 
          accounts of plan participants.  Shares accrued to the 
          individual accounts of Bruce J. Hach and Gary R. Dreher are 
          reflected in the table above and the amounts of the shares 
          being held in said individual accounts are given in footnotes 
          5 and 6 to the above table. See footnote 3 to the above table 
          with reference to the power to vote ESOP shares. 

     (3)  These shares are allocated to the accounts of the individual employees
          of Hach Company who are participants in the Hach ESOP, and who have 
          the power to vote the shares.  The Trustees and Hach have investment 
          power over the stock held in the 



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 4

          Plan.  The business address of the ESOP is 5600 Lindbergh Drive, 
          Loveland, Colorado  80537.

     (4)  The shares reported in the above table include shares of 
          Existing Common Stock which can be acquired within 60 days of  
          March 2, 1998 through the exercise of options:  Mr. Hach - 
          10,666 Common, 10,666 Class A; Mr. Dreher - 20,666 Common, 
          20,666 Class A; Mr. Schwan - 11,089 Common, 11,089 Class A; 
          Ms. Doty - 11,089 Common, 11,089 Class A; Mr. McConnell - 
          11,089 Common, 11,089 Class A; and Mr. Wenninger - 11,089 
          Common, 11,089 Class A; and Directors and executive officers 
          as a group - 140,270 Common, 140,270 Class A.  Each individual 
          option shares are also included in the number of shares of the 
          Company issued and outstanding for purposes of calculating the 
          percentage ownership of each individual in accordance with the 
          rules and regulations of the Securities Exchange Act of 1934, 
          as amended.  These persons also have options not exercisable 
          within 60 days of March 2, 1998 by which they can acquire the 
          following additional shares of Existing Common Stock:  Mr. 
          Hach - 9,334 Common, 27,334 Class A; Mr. Dreher - 9,334 
          Common, 27,334 Class A; and Directors and executive officers 
          as a group - 57,337 Common, 164,337 Class A.  These shares are 
          not included in the above table or in the percentage ownership 
          calculations.

     (5)  Excludes 64,644 shares held by Robert O. Case and Bruce 
          J. Hach as co-trustees of eight irrevocable trusts for the 
          benefit of the grandchildren of Kathryn Hach-Darrow.  Robert 
          O. Case and Bruce J. Hach have shared investment and voting 
          powers with respect to those shares.  Three of the 
          beneficiaries of the trusts are the children of Bruce J. Hach. 
          Also excludes 206,400 shares held in separate shares in an 
          irrevocable trust for the benefit of the grandchildren of 
          Kathryn Hach-Darrow by Bank One - Loveland under an agreement 
          dated June 30, 1975, between Kathryn Hach-Darrow and the late 
          Clifford C. Hach as settlors, and The Northern Trust Company, 
          as initial trustee.  The Trust is being held for the benefit 
          of the grandchildren of Kathryn Hach-Darrow and the late 
          Clifford C. Hach, three of whom  are the children of Bruce J. 
          Hach.  Also excludes 87,047 shares held by a partnership 
          composed of the children of Kathryn Hach-Darrow and their 
          spouses.  Includes 5,612 shares held by the Hach ESOP which 
          are accrued to the account of Bruce J. Hach and which he has 
          the right to direct the Plan trustee to vote.



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 5

     (6)  Includes 3,926 shares held by the Hach ESOP which are 
          accrued to the account of Mr. Dreher and which he has the 
          right to direct the Plan trustee to vote.  Excludes an 
          additional 698,836 shares owned by the Hach ESOP, for which 
          Mr. Dreher as a co-trustee of the ESOP shares investment power.

     (7)  Includes the shares listed in the table above opposite 
          Kathryn Hach-Darrow's name.  Excludes (i) 144,300 shares held 
          by the Hach's 401(k) Plan for the individual accounts of 
          employees, other than executive officers and directors of 
          Hach, (ii)  678,700 shares held by the Hach ESOP, which are 
          allocated to the individual accounts of employees other than 
          executive officers or directors of the Company, (iii)  271,044 
          shares referred to in footnote 5 to the table above, and (iv)  
          87,047 shares held by a partnership composed of the children 
          of Kathryn Hach-Darrow and the late Clifford C. Hach and their 
          spouses, as to which Bruce J. Hach, the President and a 
          Director of the Company, is a partner.  If all the shares 
          referred to in the preceding sentence were included, the 
          shares beneficially owned by officers and directors as a group 
          would be 6,220,366 Common and 6,221,866 Class A,  and the 
          percent of each class would be 74.05% and 74.20% respectively.

          Hach maintains its accounting on a fiscal year basis, with an April 
     30 year end, and computes its income under the accrual method of 
     accounting.  Hach is the parent corporation of an affiliated group of 
     subsidiaries ("Hach Group"). The Hach Group files a consolidated federal 
     income tax return and will continue to file consolidated federal income 
     tax returns after the effective time of the Merger.

          B.   HACH ACQUISITION CORP.

          Mergerco will have its principal office at 5600 Lindbergh Drive, 
     Loveland, Colorado 80538.   Mergerco will be a corporation duly 
     incorporated and existing under the laws of the State of Delaware.  
     Mergerco will not own or operate any subsidiaries.  Mergerco will have 
     1,000 shares of voting, no par value, common stock authorized, all of 
     which will be issued and outstanding and held by Hach.



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 6

          Mergerco will maintain its accounting on a fiscal year basis, with 
     an April 30 year end, and computes its income under the accrual method 
     of accounting. Mergerco will file as a member of the Hach Group's 
     consolidated federal income tax return.  

          C.   ENVIRONMENTAL TEST SYSTEMS, INC.

          ETS maintains its principal office at 23575 County Road 106, 
     Elkhart, Indiana  46514.  ETS is a corporation duly incorporated and 
     existing under the laws of the State of Indiana.  As of December 31, 
     1997, ETS had 300,000 shares of voting, no par value, Class A common 
     stock authorized, of which approximately 231,304 shares were issued and 
     outstanding ("ETS Class A Common Stock"), and 1,000,000 shares of 
     voting, no par value Class B common stock, of which approximately 
     692,228 shares were issued and outstanding ("ETS Class B Common Stock")  
     (collectively, the ETS Class A Common Stock and the ETS Class B Class 
     Common Stock are hereinafter referred to as the "ETS Common Stocks").  

          The ETS Common Stocks are not actively traded and there has never 
     been an established public trading market for ETS's stock.    ETS has no 
     class or series of capital stock authorized other than the ETS Common 
     Stocks.  There are no options, warrants, commitments, calls, puts, 
     agreements, understandings, arrangements or subscription rights relating 
     to any shares of ETS Common Stocks, or any securities convertible into 
     or representing the right to purchase or otherwise acquire any common 
     stock or debt securities of ETS, by which ETS is or may become bound.

          The following table sets forth certain information as of March 1, 
     1998 as to the beneficial ownership of the outstanding ETS Common Stocks 
     by each person known by ETS to own beneficially more than 5% of the 
     outstanding shares of each class of ETS Common Stocks, by each director 
     and named executive officer of ETS and by all current directors and 
     executive officers of ETS as a group: 



               NAME                             ETS CLASS A COMMON STOCK   ETS CLASS B COMMON STOCK
               ----                             ------------------------   ------------------------
                                                Number of      Percent      Number of      Percent
                                                 Shares                     Shares


Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 7

                                                                                
     
     Harry T. Stephenson (1) ..............          - -            - -        476,756         68.87%
     
     Environmental Test Systems Inc.
     Employee Stock
       Ownership Plan and Trust(1) ........      231,304           100%            - -            - -
     
     John R. Gildea(1) ....................          - -            - -        125,472         18.13%
     
     Robert C. Boguslaski(1) ..............          - -            - -         90,000         13.00%
     
     Mark J. Stephenson ...................          - -            - -            - -            - -
     
     John P. Simon(2) .....................          227              *            - -            - -
     
     Kenneth A. Blake(2)                             245              *            - -            - -
     
     David A.N. Morris                               - -            - -            - -            - -
     
     All current executive officers and
     directors as a group                            775              *        602,228         87.00%


     *    less than 1%
     
     (1)  The business address for each of Harry T. Stephenson, the ETS ESOP and
          John Gildea is c/o Environmental Test Systems, Inc. 23575 County Road,
          106, P.O. Box 4659, Elkhart, Indiana  46514-0659.  The business 
          address for Robert C. Boguslaski is c/o Serim Research Corporation, 
          23565 Reedy Drive, Elkhart, Indiana  46514.
     
     (2)  Represents shares allocated under the ETS ESOP in 1996.  Allocations 
          for 1997 are not calculable at this time.
     
          ETS maintains its accounting on a calendar year basis, and computes 
     its income under the accrual method of accounting.  ETS is the parent 
     corporation of one (1) subsidiary (collectively, the "ETS Group").  The ETS
     Group files a consolidated federal income tax return.
     



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 8

                                       BUSINESS PURPOSES

          The shareholders of Hach and the shareholders of ETS desire to 
     reorganize their stock interests to accomplish the following business 
     objectives:

          1.   To obtain greater financial and managerial strength for future 
     growth and to achieve economies of scale and other operational benefits.

          2.   To allow Hach and ETS to compete more effectively with other
     environmental services providers and to enable ETS to provide new or 
     broader services to its customers.

          3.   To provide the shareholders of ETS an interest in a more widely
     held enterprise that is potentially more liquid than the ETS Common Stocks.

          4.   To allow Hach greater access to the environmental services 
     market in the Elkhart, Indiana area.


                                 PROPOSED TRANSACTION

          As used herein, "Code" refers to the Internal Revenue Code of 1986, 
     as amended, and "Regulations" refers to regulations promulgated 
     thereunder by the Secretary of the Treasury, all as in effect as of the 
     date of this opinion.

          To accomplish the objectives specified above, Hach, Mergerco and 
     ETS have entered into an Agreement and Plan of  Merger, dated January 
     21, 1998 ("Agreement").  Pursuant to the Agreement, the Merger will 
     involve the merger of ETS with and into Mergerco, with Mergerco as the 
     surviving entity.  Mergerco will continue as a wholly-owned subsidiary 
     of Hach. 

          At the Effective Time, by virtue of the Merger and without any 
     action on the part of Hach, Mergerco, ETS or the holder of any of the 
     following securities:



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 9

               (i)  each share of ETS Class A Common Stock issued and 
          outstanding immediately prior to the Effective Time (as defined in 
          the Agreement) shall be converted into and become a right to 
          receive per share (A) at Closing (as defined in the Agreement) that 
          number of shares of Hach Common Stock as shall have an aggregate 
          value equal to $17.465651, with each share of  Hach Common Stock 
          valued at the average of its daily closing prices on the Nasdaq 
          National Market over a 20 day period ending five business days 
          prior to the Effective Time and (B) a proportionate share of the 
          consideration delivered into escrow at Closing, subject to the 
          terms of the escrow (collectively, the "Class A Merger 
          Consideration"); and

          (ii) each share of ETS Class B Common Stock issued and 
          outstanding immediately prior to the Effective Time shall be 
          converted into and become a right to receive per share (A) at 
          Closing (1) cash, (2) that number of shares of Hach Common Stock 
          and (3) that number of shares of Hach Class A Common Stock, as 
          shall have an aggregate value equal to $14.749656, with each of the 
          Hach Common Stocks valued at the average of its daily closing 
          prices on the Nasdaq National Market over a 20 day period ending 
          five business days prior to the Effective Time and (B) a 
          proportionate share of the consideration delivered into escrow at 
          Closing, subject to the terms of the escrow (collectively, the 
          "Class B Merger Consideration").  Hach shall have the right, in its 
          sole discretion, to determine the allocation of the components of 
          the consideration to be paid to the holders of ETS Class B Common 
          Stock; provided that (x) the aggregate values of the Hach Class A 
          Common Stock issued upon the Merger and Hach Common Stock shall be 
          equal and (y) the cash to be paid will not be less than $6,878,400 
          or greater than $7,343,875.
     
          In order to provide for the payment and satisfaction of certain 
     indemnification obligations contained in the Agreement, cash and 
     Hach Common Stocks with an aggregate value of $1,750,000 (allocated 
     among the ETS shareholders in the same proportion as the 
     consideration delivered to ETS shareholders at Closing) will be 
     held in escrow by an escrow agent, pursuant to the terms and 
     considers of an escrow agreement to be signed and delivered at 
     Closing.  Subject to the satisfaction of the indemnification 
     obligations secured by the escrow, the cash and shares of Hach 
     Common Stocks will be released from the escrow on the third 
     anniversary of the Effective Time.  Dividends and distributions 
     with respect to the Hach Common Stocks held in escrow will be paid 
     to the escrow agent and held as part of the 



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 10

     escrow deposit, subject to release from time to time on terms and 
     conditions as described in the escrow agreement.

          No fractional shares of the Hach Common Stocks will be issued 
     with respect to fractional share interests arising from the 
     exchange ratio specified above. Rather, any shareholder of ETS 
     entitled to a fractional share interest of the Hach Common Stocks 
     will receive cash in lieu thereof in an amount equal to such 
     fraction multiplied by the Average Price Per Share (as defined in 
     the Agreement) of the Hach Common Stocks.  The payment of cash in 
     lieu of fractional share interests of the Hach Common Stocks is 
     solely for the purpose of avoiding the expense and inconvenience to 
     Hach of issuing fractional shares and does not represent separately 
     bargained-for consideration.  

          No cash or other property, except for Merger consideration as 
     described above and cash paid in lieu of fractional shares, will be 
     allocated to the shareholders of ETS.  Shareholders of ETS who 
     properly exercise and perfect statutory dissenters' rights shall 
     have the rights accorded to dissenting shareholders under Indiana 
     Business Corporation Law, as amended.

          The Agreement will be submitted to the shareholders of ETS for 
     approval at a meeting called and held in accordance with applicable 
     law and the Articles of Incorporation  and By-Laws of ETS.  
     Approval of the Merger by the shareholders of Hach is not 
     contemplated or required.  The Merger requires approval by the 
     Boards of Directors of Hach and ETS.

          The proposed Merger is subject to approval by the Federal 
     Trade Commission. The above-referenced regulatory agency has 
     approved the Merger.

          The shares of the Hach Common Stocks will, when issued to 
     non-dissenting shareholders of ETS in accordance with the 
     Agreement, be validly issued, fully paid and nonassessable and 
     registered under the Securities Act of 1933, as amended.




Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 11

                                     ASSUMPTIONS

          In connection with the Merger, we have relied upon the 
     following assumptions for the purpose of issuing this opinion:  

          1.   As Hach owns one hundred percent (100%) of the capital 
     stock of Mergerco, no additional Mergerco capital stock is being 
     issued or exchanged in the Merger.

          2.   There is no plan or intention by the shareholders of ETS 
     who own one percent (1%) or more of the shares of the ETS Common 
     Stocks, and there is no plan or intention on the part of the 
     remaining shareholders of ETS, to sell, exchange or otherwise 
     dispose of a number of shares of the Hach Common Stocks received in 
     the Merger that would reduce the ETS shareholders' ownership of the 
     Hach Common Stocks to a number of shares having a value, as of the 
     effective time of the Merger, of less than fifty percent (50%) of 
     the value of all of the formerly outstanding shares of the ETS 
     Common Stocks as of the same date.  For purposes of this 
     assumption, shares of the ETS Common Stocks exchanged for cash or 
     other property, surrendered by dissenters or exchanged for cash in 
     lieu of fractional shares of the Hach Common Stocks will be treated 
     as outstanding the ETS Common Stocks as of the effective time of 
     the Merger.  Moreover, shares of The ETS Common Stocks and shares 
     of The Hach Common Stocks held by ETS shareholders and otherwise 
     sold, redeemed, or disposed of prior or subsequent to the effective 
     time of the Merger will be considered in making this assumption. No 
     ETS shareholders will exercise their dissenter's rights. 

          3.   Mergerco will acquire at least ninety percent (90%) of 
     the fair market value of the net assets and at least seventy 
     percent (70%) of the fair market value of the gross assets held by 
     ETS immediately prior to the Merger.  For purposes of this 
     assumption, amounts paid by ETS to dissenters, amounts paid by ETS 
     to shareholders who receive cash or other property, amounts of ETS 
     assets used to pay its reorganization expenses, and amounts of  all 
     redemptions and distributions (except for regular, normal 
     dividends) made by ETS immediately preceding the transfer, will be 
     included as assets of ETS held immediately prior to the effective 
     time of the Merger. 

          4.   Prior to the Merger, Hach will be in control of Mergerco 
     within the meaning of Section 368(c) of the Code.



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 12

          5.   Following the Merger, Mergerco will not issue additional 
     shares of its common stock that would result in Hach losing control 
     of Mergerco within the meaning of Section 368(c) of the Code.

          6.   Mergerco has no plan or intention to reacquire any of its 
     common stock constructively issued in the Merger.  Hach has no plan 
     or intention to reacquire any of its common stock issued in the 
     Merger other than through unrelated periodic purchases on an 
     anonymous basis on the open market at open market prices.

          7.   Hach has no plan or intention to liquidate Mergerco; to 
     merge Mergerco with and into another corporation; to sell or 
     otherwise dispose of the common stock of Mergerco; or to cause 
     Mergerco to sell or otherwise dispose of any of the assets of ETS 
     acquired in the Merger, except for dispositions made in the 
     ordinary course of business or transfers described in Section 
     368(a)(2)(C) of the Code.

          8.   The liabilities of ETS assumed by Mergerco and the 
     liabilities to which the transferred assets of ETS are subject were 
     incurred by ETS in the ordinary course of its business.

          9.   The fair market value of the Hach Common Stocks and other 
     consideration received by each ETS shareholder will be 
     approximately equal to the fair market value of the ETS Common 
     Stocks surrendered in the exchange.

          10.  Following the Merger, Mergerco will continue the historic 
     business of ETS or use a significant portion of ETS's historic 
     business assets in a business.

          11.  Hach, Mergerco, ETS and the shareholders of ETS will pay 
     their respective expenses, if any, incurred in connection with the 
     Merger.

          12.  There is no intercorporate indebtedness existing between 
     Hach and  ETS or between Mergerco and ETS that was issued, acquired 
     or will be settled at a discount.

          13.  No two parties to the Merger are investment companies as 
     defined in Section 368(a)(2)(F)(iii) and (iv) of the Code.



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 13

          14.  ETS is not under the jurisdiction of a court in a Title 
     11 or similar case within the meaning of Section 368(a)(3)(A) of 
     the Code.

          15.  The fair market value of the assets of ETS transferred to 
     Mergerco will equal or exceed the sum of the liabilities assumed by 
     Mergerco plus the amount of liabilities, if any, to which the 
     transferred assets are subject.

          16.  The payment of cash in lieu of fractional shares of the 
     Hach Common Stocks resulting from the Merger exchange ratio under 
     the Agreement is solely for the purpose of avoiding the expense and 
     inconvenience to Hach of issuing fractional shares of the Hach 
     Common Stocks and does not represent separately bargained-for 
     consideration.  The total cash consideration that will be paid in 
     the Merger to ETS shareholders instead of issuing fractional shares 
     of the Hach Common Stocks will not exceed one percent (1%) of the 
     total consideration that will be issued in the Merger to the ETS 
     shareholders in exchange for their shares of the ETS Common Stocks. 
     The fractional share interests of each ETS shareholder will be 
     aggregated, and no ETS shareholder will receive cash in an amount 
     equal to or greater than the value of one (1) full share of the 
     Hach Common Stocks.

          17.  None of the compensation received by any 
     shareholder-employee of ETS will be separate consideration for, or 
     allocable to, any of their shares of the ETS Common Stocks; none of 
     the shares of the Hach Common Stocks received by any 
     shareholder-employee of ETS will be separate consideration for, or 
     allocable to, any employment agreement; and the compensation paid 
     to any shareholder-employee of ETS will be for services actually 
     rendered and will be commensurate with amounts paid to third 
     parties bargaining at arm's-length for similar services.

                                       OPINION

          Based solely upon the facts, assumptions and other information 
     set forth herein, and so long as such facts, assumptions and other 
     information are true and correct on the date of consummation of the 
     Merger, it is our opinion with respect to the Merger that:

          1.   Provided that the merger of ETS with and into Mergerco qualifies
               as a statutory merger under applicable law, and, following the 
               Merger, Mergerco 



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 14


               will hold substantially all of its assets and the assets of
               ETS, and, in the Merger the shareholders of ETS will 
               constructively exchange an amount of stock constituting 
               control of ETS (within the meaning of Section 368(c) of 
               the Code) solely for voting Hach Common Stocks, the proposed
               merger will constitute a reorganization within the meaning 
               of Section 368(a)(1)(A) and Section 368(a)(2)(D) of 
               the Code.  The reorganization will not be disqualified by 
               reason of the fact that voting stock of Hach is being used 
               in the merger.  For purposes of this opinion, "substantially
               all" means at least ninety percent (90%) of the fair market 
               value of the net assets and at least seventy percent (70%) 
               of the fair market value of the gross assets of ETS.  Hach, 
               Mergerco and ETS will each be a "party to a reorganization" 
               within the meaning of Section 368(b) of the Code.

          2.   No gain or loss will be recognized by ETS on the transfer of
               substantially all of its assets to Mergerco and the assumption by
               Mergerco of the liabilities of ETS.

          3.   No gain or loss will be recognized by Hach or Mergerco on the 
               receipt by Mergerco of substantially all of the assets of ETS in 
               constructive exchange for the Hach Common Stocks and the 
               assumption by Mergerco of ETS's liabilities.

          4.   No gain or loss will be recognized by the shareholders of ETS 
               upon the deemed exchange of the ETS Common Stocks solely for the 
               Hach Common Stocks.

          The opinions expressed herein represent our conclusions as to 
     the application of existing federal income tax law to the facts as 
     presented to us relating to the Merger, and we give no assurance 
     that changes in such law or any interpretation thereof will not 
     affect the opinions expressed by us.  Moreover, there can be no 
     assurance that these opinions will not be challenged by the 
     Internal Revenue Service or that a court considering the issues 
     will not hold contrary to such opinions.  We express no opinion on 
     the treatment of the Merger under the income tax laws of any state 
     or other taxing jurisdiction.  We assume no obligation to advise 
     you of any changes concerning the above, whether or not deemed 
     material, which 



Environmental Test Systems, Inc.
Hach Company
March 24, 1998
Page 15

     may hereafter come or be brought to our attention.  The opinions 
     expressed herein are a matter of professional judgment and are not 
     a guarantee of result.

          This opinion letter is addressed to you and is solely for your 
     use in connection with the Merger and your role as members of your 
     respective Boards of Directors.  We assume no professional 
     responsibility to any other person or entity whatsoever, including, 
     without limitation, any shareholder of Hach or any shareholder of 
     ETS.  Accordingly, the opinions expressed herein are not to be 
     utilized or quoted by, or delivered or disclosed to, in whole or in 
     part, any other person, corporation, entity or governmental 
     authority without, in each instance, our prior written consent.

                                 Very truly yours,


                                /s/KRIEG DeVAULT ALEXANDER & CAPEHART
                                KRIEG DeVAULT ALEXANDER & CAPEHART