San Mateo County, California — public water systems

How does San Mateo County compare with other California counties?

San Mateo County has the 45th-most active public water systems among the 201 counties listed for active California systems in EPA records; among the 72 with 3 or more systems, the median has 73. Its systems report 783,522 people served in total, the 13th-largest county figure in the state and 1.8% of the statewide total. The average system here reports serving 15,363 people, about 169% above the California average of 5,706. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does San Mateo County's drinking water come from?

By primary water source, San Mateo County's active systems draw on purchased surface water (17, 33%), surface water (15, 29%), groundwater (15, 29%) and groundwater under influence of surface water (4, 7.8%). Overall, 37% rely mainly on groundwater (including purchased groundwater) and 63% on surface water, compared with 85% and 15% across California. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. The county's largest system, City of Daly City, draws primarily on purchased surface water.

What kinds of water systems operate in San Mateo County?

San Mateo County's active systems break down as 36 community systems (71%), 2 non-transient non-community systems (3.9%) and 13 transient non-community systems (25%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (53%), local government (37%) and state government (9.8%).