Exhibit 21 Subsidiaries of Registrant SUBSIDIARIES OF REGISTRANT 1.0 American States Water Company (Commission File No. 333-47647) 1.1 Southern California Water Company 1.2 American State Utility Services 1.3 Chaparrel City Water Company 2.0 Southern California Water Company (Commission File No. 000-01121) 2.1 No material subsidiaries