EXHIBIT 99.1 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 CUNO Incorporated (the "Company") on Form 10-Q for the period ended July 31, 2002 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), I, Mark G. Kachur, Chief Executive Officer; and Frederick C. Flynn, Jr.; Chief Financial Officer of the Company, certify, 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; and (2) The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company. /s/ Mark G. Kachur - --------------------------- Mark G. Kachur Chief Executive Officer August 21, 2002 /s/ Frederick C. Flynn, Jr. - --------------------------- Frederick C. Flynn, Jr. Chief Financial Officer August 21, 2002 25