Formed in 1926, California Water Service Company operates one of the largest water utilities in the United States. Located in Commerce, Calif., it serves more than 460,000 customers through 28 customer/operations centers throughout the state. Cal Water Service Company is a subsidiary of the California Water Service Group. The firm along with its six subsidiaries offers expertise in operating water/wastewater systems and provides related utility services. California Water Service Group serves approximately two million people in over 100 communities.