San Mateo County Water Department

Find San Mateo County California water departments, districts, authorities, boards, and services. Water departments provide information on drinking water, treatment plants, sewage treatment, water conservation, and testing.


Calera Creek Water Department 700 Coast Hwy Pacifica CA 94044 650-738-4660


Daly City Water Department 153 Lake Merced Boulevard Daly CA 94015 650-991-8200

East Palo Alto Water Department 2415 University Avenue East Palo Alto CA 94303 650-363-4000

Hillsborough Town Water Department 1320 La Honda Road Hillsborough CA 94010 650-375-7402

Millbrae Water Department 400 Millbrae Avenue Millbrae CA 94030 650-259-2388

San Bruno Water Department 225 Huntington Avenue San Bruno CA 94066 650-616-7162

San Francisco Water Department 1000 El Camino Real Millbrae CA 94030 650-872-5900

About San Mateo County Water Departments

The San Mateo County Water Department or Water Utility is a government agency or private company that operates a public water system, which provides potable tap water directly to residential, commercial, industrial, and institutional customers in San Mateo County, CA.

You may contact the Water Department for questions about:
  • Water utility bills and payments
  • San Mateo County drinking water
  • Drinking water quality testing and safety
  • Water treatment facilities in San Mateo County, CA
San Mateo County Water Utility Companies

Water Departments in San Mateo County operate as an utility and are self-sustaining operations funded through user fees. San Mateo County water rates may be subject to approval from a state regulatory authority such as a California Public Service Commission or Utility Control Authority.

Public Drinking Water

Water Departments, or Water Companies in San Mateo County typically own the sources of drinking water they provide and must manage and maintain those sources and their surrounding areas. Surface sources include reservoirs, lakes, and rivers. San Mateo County groundwater sources can be found in pockets beneath the ground, which can be accessed by drilling wells. Maintenance of San Mateo County drinking water source sites and limitations on permitted activity around water sources helps minimize contamination. However, drinking water requires treatment prior to distribution to customers.

Water Treatment Facilities in San Mateo County, CA

San Mateo County water treatment facilities are used to remove contaminants and make drinking water safe for consumption. Treatment of water begins with the removal of the larger particles in the water through processes known as coagulation, flocculation, and sedimentation. After the large particles are removed, water is filtered through materials such as sand, gravel, and charcoal to remove dissolved particles. The final stage of treatment involves disinfection using chemicals or ultraviolet irradiation. San Mateo County Water Departments may add fluoride to water at this stage as part of a community health effort to support oral health in the general population. Water Departments are responsible for the day-to-day operations and maintenance of San Mateo County water treatment facilities. Equipment must also be periodically replaced and treatment processes may also be periodically upgraded.

From the treatment plant, water reaches its customers through a distribution system consisting of pipes, referred to as water mains, storage tanks, and pumping stations. Individual customers connect to water mains to bring public drinking water directly to their properties in San Mateo County, California.

Water Testing in San Mateo County

Water Companies typically have a laboratory or testing division responsible for monitoring the quality of tap water throughout the process, from source to distribution. California state regulations require Water Utilities to prepare and issue San Mateo County water quality reports to the general public several times per year.