CALIFORNIA WATER SERVICE GROUP

California Water Service Group (Company) is a holding company with seven operating subsidiaries: Cal Water, Washington Water Service Company (Washington Water), New Mexico Water Service Company (New Mexico Water), Hawaii Water Service Company, Inc. (Hawaii Water), TWSC, Inc. (Texas Water), CWS Utility Services, and HWS Utility Services LLC (CWS Utility Services and HWS Utility Services LLC being referred to collectively in this annual report as Utility Services). Cal Water, Washington Water, New Mexico Water, and Hawaii Water are regulated public utilities. Texas Water is a holding company with regulated water and wastewater utilities.

The regulated utility entities also provide non-regulated services. Utility Services holds non-utility property and provides non-regulated services to private companies and municipalities outside of California (see “Non-Regulated Activities” below for more details). Cal Water was the original operating company that began operations in 1926.

Our business is conducted through our operating subsidiaries and we provide utility services to approximately two million people. The bulk of our business consists of the production, purchase, storage, treatment, testing, distribution, and sale of water for domestic, industrial, public, and irrigation uses, and the provision of water for domestic and municipal fire protection services. In some areas, we provide wastewater collection and treatment services, including treatment that allows water recycling. We also provide non-regulated water-related services under agreements with municipalities and other private companies. The non-regulated services include full water system operation, meter reading, and billing services. Non-regulated operations also include the lease of communication antenna sites, lab services, and promotion of other non-regulated services.

During the year ended December 31, 2025, there were no significant changes in the kind of products produced or services rendered by our operating subsidiaries, or in the markets or methods of distribution.

Our mailing address and contact information is:

California Water Service Group

1720 North First Street

San Jose, California 95112-4598

Telephone number: 408-367-8200

www.calwatergroup.com

Annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to these reports are available free of charge through our website at www.calwatergroup.com. The reports are available on our website as soon as reasonably practicable after such reports are filed with the U.S. Securities and Exchange Commission (SEC).

The content on any website referred to in this annual report is not incorporated by reference in this annual report unless expressly noted.