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The Small Drinking Water Systems Program


The Small Drinking Water Systems Program


The State Water Board (Drinking Water Division) oversees large water systems that provide drinking water for most of the public. This includes water systems that serve 15 or more service connections or 25 people daily for at least 60 days out of the year. 

San Mateo County Environmental Health regulates smaller systems under the State Small Water Systems Program. A State Small Water System is a system that serves water to 5 to 14 service connections and fewer than 25 people daily for at least 60 days out of a year. These systems are usually found in rural areas. Environmental Health ensures that State Small Water Systems provide safe drinking water in adequate supply and under adequate pressure.

County Services

Environmental Health staff enforce the California Safe Drinking Water Act (SDWA), which regulates water quality, maintenance, and systems design. They perform the following functions:

  • Inspect water sources, treatment and distribution facilities.
  • Review test results to determine the presence of bacteria in State Small Water Systems. If any bacteria is present, staff notify water system operators of actions they must take.
  • Respond to complaints about poor water quality, contamination or suspected waterborne illness. In the event of an illness confirmed by a physician or a disaster, staff can implement emergency actions.
  • Issue permits for water suppliers. Staff review and approve permit applications to make sure the system has the equipment, staff and resources it needs.
  • Advise system operators on how to comply with regulations. Staff help water companies develop their own inspection and testing programs.
  • Revoke operating permits or work with district/city attorneys to prosecute operators who refuse to comply with regulations.
  • Supervise construction, rebuilding and destruction of water wells. Staff approve development of new sources of drinking water.
  • Review and approve changes of ownership of water systems.

Public Concerns

If you are concerned about the quality of your water, your local supplier is required by law to give you information at your request.

If you are not satisfied after reviewing water company data, you can hire a local state certified laboratory to analyze your tap water. The lab will give you sample containers and collection procedures. You can test for bacteria, iron, lead and copper or other contaminants.  For a complete list of certified laboratories, please visit the State Water Resources Control Board, Division of Drinking Water.

Environmental Health does not routinely sample individual residents’ water supply.

Sediment Coming from Tap Water

If sediment is coming from out of your hot water line, it is probably caused by rust in your water heater or your plumbing. It is not dangerous to your health. You can correct it by flushing or repairing your water heater or pipes.

If sediment is coming out of your cold water line, it is probably caused by rust in the distribution mains in the street. It can happen when water mains are shaken due to earthquakes or when heavy equipment is used near the mains. The fire department can also cause sediment to break loose by opening hydrants, causing the mains to shake. It is not a health hazard. The sediment should gradually dissipate and disappear.

Can Water Make Me Sick?

Not likely. Outbreaks of waterborne disease are very rare. Public water systems must routinely test their water quality. If there are signs of contamination, the system is required by law to notify the public immediately.

If you become ill and you don’t know why, contact your physician. Your doctor is required to report certain illnesses to the Health Department. Environmental Health can investigate water systems and put emergency safety procedures into effect if necessary.

State Small Water Systems Regulated by San Mateo County

Cascade Ranch Water System
Pescadero, CA

Dearborn Spring Water System
Pescadero, CA 94060

Djerassi Resident Artists Program Water System
Woodside, CA 94062

Echo Valley Water Coop
Loma Mar, CA

Jacobs Farm/Del Cabo
Pescadero, CA

La Honda Properties
La Honda, CA

La Honda Vista Water Company
La Honda, CA

Ano Nuevo Ranch
Pescadero, CA

Westland Nursery #2
Pescadero, CA