EXHIBIT 32.1


          CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED
            PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Quarterly Report of Ionics, Incorporated (the "Company")
on Form 10-Q for the quarter ended June 30, 2004 as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), the undersigned
hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.       The Report fully complies with the requirements of Section 13(a) or
         15(d) of the Securities Exchange Act of 1934, as amended; and

2.       The information contained in the Report fairly presents, in all
         material respects, the financial condition and results of operations of
         the Company.



                                    /s/Douglas R. Brown
                                    -------------------------------------------
                                    Douglas R. Brown
                                    President and Chief Executive Officer

Date:  August 9, 2004



                                      -1-


                                                                   EXHIBIT 32.2


          CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED
            PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Quarterly Report of Ionics, Incorporated (the "Company")
on Form 10-Q for the quarter ended June 30, 2004 as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), the undersigned
hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.       The Report fully complies with the requirements of Section 13(a) or
         15(d) of the Securities Exchange Act of 1934, as amended; and

2.       The information contained in the Report fairly presents, in all
         material respects, the financial condition and results of operations of
         the Company.



                                 /s/Daniel M. Kuzmak
                                 ----------------------------------------------
                                 Daniel M. Kuzmak
                                 Vice President and Chief Financial Officer

Date:  August 9, 2004



                                      -2-