COASTSIDE COUNTY WATER DISTRICT

HALF MOON BAY, CA · ~18,940 people served

Check your exact address → HALF MOON BAY overview

100

Excellent

PurityRadar safety score

PWSID

CA4110011

State

California

City

HALF MOON BAY

Population served

18,940

Primary source

Surface water

Score history

No change since tracking began Jun 18, 2026.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 100

2 score updates logged since tracking began Jun 18, 2026. Each future EPA re-score adds a point.

PFAS & contaminant readings

No PFAS detections are on record for this system from EPA’s UCMR5 monitoring (2023–25). Absence of a detection isn’t a guarantee — not every system was sampled, and this dataset doesn’t cover other contaminants.

Violations & enforcement

Violations on record

Unaddressed

Health-based

Enforcement actions

From EPA ECHO (SDWIS), most recent enforcement Feb 2018. Official EPA record →

Treatment technique · EPA contaminant 0200 health-based began Apr 2008 Resolved

Treatment technique · EPA contaminant 0200 health-based began Jun 2005 Resolved

Monitoring & reporting · EPA contaminant 0200 began Feb 2005 Resolved

Max contaminant level (MCL) · Total coliform health-based began Jan 2004 Resolved

Monitoring & reporting · Total coliform began Jul 2003 Resolved

Max contaminant level (MCL) · Total coliform health-based began Jan 2002 Resolved

Monitoring & reporting · Nitrate began Oct 2001 Resolved

Monitoring & reporting · Nitrate began Jul 2001 Resolved

Max contaminant level (MCL) · Total coliform health-based began Nov 1998 Resolved

Other · Total coliform began Feb 1996 Resolved

Max contaminant level (MCL) · Total coliform health-based began Feb 1996 Resolved

Monitoring & reporting · Total coliform began Feb 1996 Resolved

Recent enforcement actions

State action · SOX Feb 2018
State action · SOX Feb 2018
State action · SFL Jun 2008
State action · SOX Jun 2008
State action · SOX Dec 2005
State action · SOX Aug 2005
State action · SIE Jul 2005
State action · SOX Feb 2004

Area water-quality monitoring

Environmental monitoring (rivers, wells, intakes) recorded in this system’s service area in the EPA/USGS Water Quality Portal since 2018 — source/ambient water, not finished tap water. Context for the watershed, not a reading from your tap.

ContaminantMedian · max · samples

Copper

1 station · latest Jul 2020

0.4 · max 0.43 ug/L · 2

Nitrate

1 station · latest May 2020

0.39 · max 0.39 mg/L · 1

Source: Water Quality Portal (EPA/USGS/state agencies). Values are as-reported and aren’t health thresholds.

This profile is built from EPA public records for system CA4110011 — SDWIS violations and UCMR5 PFAS sampling. The score is system-level and can’t account for your home’s plumbing (older pipes can add lead at the tap). For health decisions, check your exact address, read the utility’s Consumer Confidence Report, and confirm with your provider.