Tap Truth EPA drinking water records, in plain English

County drinking water records

San Mateo County, CA drinking water systems

35 community water systems serve San Mateo County, CA, reporting 779,338 people served in all.

8 of them (23%) had at least one health-based violation in the last 10 years. 1 system still has one unresolved.

7 rely mainly on groundwater and 28 on surface water, counting water bought from other systems.

Their lead service line inventories list 1 lead line, 20 galvanized lines that must be replaced and 43,454 lines of unknown material.

1 more system is placed in San Mateo County, CA by the county its records name because it has no service area map that lines up with its own records, so it is listed apart and not counted here.

Community water systems
35
People served, sum of each system's own figure
779,338
Systems with a health-based violation, last 10 years
8
Systems with one unresolved
1
Lead service lines in inventories
1

Water systems serving San Mateo County

35 systems

People served is each system's own figure for its whole service area. Violation counts cover the last 10 years of EPA records.

System Serves People served Main source Health-based violations, 10 years Unresolved Lead lines
City of Daly City Daly City 104,901 Purchased surface water 0 0 0
California Water Service - San Mateo San Mateo, Highlands and 1 more 102,348 Purchased surface water 0 0 0
City of Redwood City Redwood City and Emerald Lake Hills 92,819 Purchased surface water 0 0 0
California Water Service-S San Francisco South San Francisco, Colma and 1 more 64,146 Purchased surface water 0 0 0
California Water Service - Bear Gulch Woodside, Portola Valley and 6 more and land outside them 61,431 Surface water 0 0 0
City of San Bruno San Bruno 42,631 Purchased surface water 0 0 0
North Coast County Water Dist Pacifica 38,546 Purchased surface water 0 0 0
Estero Municipal Improvement District Foster City and San Mateo 36,556 Purchased surface water 0 0 0
California Water Service - San Carlos San Carlos 35,344 Purchased surface water 0 0 0
City of Burlingame Burlingame 31,451 Purchased surface water 0 0 0
Mid-Peninsula Water District Belmont 30,609 Purchased surface water 0 0 0
City of East Palo Alto East Palo Alto and Menlo Park 29,519 Purchased surface water 0 0 0
City of Millbrae Millbrae 22,795 Purchased surface water 0 0 0
Menlo Park Municipal Water Menlo Park 22,362 Purchased surface water 0 0 0
Coastside County Water District Half Moon Bay and El Granada 18,940 Surface water 0 0 0
Westborough Water District South San Francisco 13,486 Purchased surface water 0 0 0
Town of Hillsborough Hillsborough 11,766 Purchased surface water 0 0 0
Montara Water and Sanitary District Montara and Moss Beach 6,078 Surface water 0 0 0
City of Brisbane Brisbane 3,402 Purchased surface water 0 0 0
Palo Alto Park Mutual Water Company East Palo Alto 2,900 Groundwater 0 0 0
O'Connor Tract Co-Operative Water Co. Menlo Park 2,789 Groundwater 1 0 0
Guadalupe Valley Mid Brisbane 1,472 Purchased surface water 0 0 0
Cuesta La Honda Guild Inc La Honda 915 Surface water 4 0 0
County Service Area 11 Pescadero 642 Groundwater 1 0 0
Camp Jones Gulch Outside cities and towns 357 Groundwater 0 0 0
County Service Area 7 La Honda 300 Surface water 6 0 0
Camp Loma Mar Outside cities and towns 208 Surface water 1 0 0
Butano Canyon Mutual Outside cities and towns 150 Surface water 0 0 1
Redwood Glen Camp & Conference Ctr Outside cities and towns 114 Surface water 0 0 0
Portola Improvement Association MWC Outside cities and towns 90 Groundwater under direct influence 0 0 0
Loma Mar Mutual Loma Mar 65 Surface water 1 0 0
Bianchi Flowers Inc Pescadero 65 Groundwater 0 0 0
Redwood Terrace Mutual Outside cities and towns 56 Groundwater under direct influence 1 0 0
Marchi Central Farm Outside cities and towns 50 Groundwater 1 0 0
Oku Incorporated Pescadero 35 Groundwater 0 1 0

Systems placed by county record in San Mateo County

1 system

EPA has no service area map for this system. It is placed by the county its records name (the counties EPA lists it serving, or the county coded in its ID where EPA lists none), and without a map it is not counted in the figures above.

System Serves People served Main source Health-based violations, 10 years Unresolved Lead lines
Puente Housing Solutions County on record 28 Groundwater under direct influence 1 0 No inventory

Cities and towns in San Mateo County

33 places

Back to California

Counties come from the counties EPA lists each system serving, matched to 2024 Census counties; where EPA lists none, from the county coded in the system's ID, its service area map, or its mailing address. A county holding at least a fifth of a system's service area map is added when at least a fifth of that map lies in those counties. Towns are the ones EPA lists and the Census places such a map covers, always inside those counties. In New England, where EPA's town names a whole Town, it is not matched to the village of the same name. A system is not listed in a county holding less than a fifth of its map, or in a county or town its map reaches when the map lies mostly outside the counties EPA lists, so a page can leave out a system that serves part of the area. Methodology and limitations