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
The Company and each of its subsidiaries operate in one business segment, the
supply and distribution of water, and providing water-related services.