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 Waters Corporation (the "Company")
on Form 10-Q for the period ending June 30, 2002 as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), I, Douglas A.
Berthiaume, Chairman and Chief Executive 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 results of operations of the Company.

                                                     /s/ Douglas A. Berthiaume
                                                     ---------------------------
                                                     Douglas A. Berthiaume
                                                     Chairman and
                                                     Chief Executive Officer