Exhibit 32

CERTIFICATION OF CEO AND CFO
PURSUANT TO 18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO SECTION 906
OF THE SARBANES-OXLEY ACT OF 2002

     Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, each of the undersigned certifies that this Quarterly Report on Form 10-Q for the period ended March 31, 2010, fully complies with the requirements of Section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934 and that the information contained in this Report fairly presents, in all material respects, the financial condition and results of operations of California Water Service Group.

Date: May 7, 2010	By:	/s/ Peter C. Nelson
		PETER C. NELSON
		President and Chief Executive Officer California Water Service Group
Date: May 7, 2010	By:	/s/ Martin A. Kropelnicki
		MARTIN A. KROPELNICKI
		Vice President, Chief Financial Officer and Treasurer California Water Service Group