Coastside County Water District

Water Quality Snapshot: Coastside County Water District

Coastside County Water District is a local-owned community water system that delivers drinking water to 18,940 residents in Half Moon Bay, California (San Mateo County) through 6,617 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 33 total violations for this system , of which 14 (42%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 16 monitoring and reporting violations are on file. The most recent violation on record dates to 2008.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 10 violations (MCL, health-based). This system was sampled under EPA's UCMR5 PFAS monitoring program and no PFAS compounds were detected above the minimum reporting level.

Across California, EPA tracks 7,249 public water systems serving 42,404,883 people, with 153,308 cumulative violations and 63,983 health-based violations on record. About 89% of systems in the state carry at least one violation, and state-wide the average per system is 21.1 violations. Statewide, 447 of 694 UCMR5-tested systems have reported PFAS detections (64.4%).

Coastside County Water District's 33 violations sit above the California average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.