EXHIBIT 15

                      ACKNOWLEDGEMENT OF ERNST & YOUNG LLP

May 21, 2003

Stockholders and Board of Directors
CUNO Incorporated

We are aware of the incorporation by reference in the Registration Statement
(Form S-8 No. 333-39763) pertaining to the CUNO Incorporated 1996 Stock
Incentive Plan, the CUNO Incorporated Non-Employee Director's Stock Option Plan,
and the CUNO Incorporated Savings and Retirement Plan and the Registration
Statement (Form S-8 No. 333-54388) pertaining to the CUNO Incorporated 1996
Stock Incentive Plan and the CUNO Incorporated Non-Employee Directors' Stock
Option Plan of our report dated May 20, 2003 relating to the unaudited condensed
consolidated interim financial statements of CUNO Incorporated that are included
in its Form 10-Q for the three-month period ended April 30, 2003.

                              /s/ Ernst & Young LLP

Hartford, Connecticut

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