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 June 19, 1998 on our audits of the financial statements of the Ionics Section 401(k) Stock Savings Plan as of December 31, 1997 and 1996, which report is included in this Annual Report on Form 11-K of the Plan which is being filed as Exhibit 13(b) to the Annual Report on Form 10-K of Ionics, Incorporated for the year ended December 31, 1997. /s/BELANGER & COMPANY P.C. CERTIFIED PUBLIC ACCOUNTANTS Chelmsford, Massachusetts June 23, 1998 -15- /25