EXHIBIT 1 CONSENT OF INDEPENDENT ACCOUNTANTS We consent to the incorporation by reference in the registration statement of the Ionics Section 401(k) Stock Savings Plan on Form S-8 (Registration No. 33-2092) of our report dated May 18, 1994 on our audits of the financial statements of the Ionics Section 401(k) Stock Savings Plan as of December 31, 1993 and 1992, and for each of the three years in the period ended December 31, 1993, which report is included in this Annual Report on Form 11-K of the Plan which is being filed as Exhibit 28 to the Annual Report on Form 10-K of Ionics, Incorporated for the year ended December 31, 1993. Coopers & Lybrand Boston, Massachusetts May 27, 1994 - - - - - -12-