Form: 10-K

Annual report pursuant to Section 13 and 15(d)

February 28, 2013


Exhibit 21

Subsidiaries of the Registrant

Subsidiary Name
  State of Incorporation   Business Name
California Water Service Company   California   California Water Service Company
CWS Utility Services   California   CWS Utility Services
New Mexico Water Service Company   New Mexico   New Mexico Water Service Company
Washington Water Service Company   Washington   Washington Water Service Company
Hawaii Water Service Company, Inc.    Hawaii   Hawaii Water Service Company
HWS Utility Services LLC   Hawaii   HWS Utility Services