CALIFORNIA WATER SERVICE - STOCKTON

SAN JOSE, CA · ~176,266 people served

Check your exact address → SAN JOSE overview

Excellent

PurityRadar safety score

PWSID

CA3910001

State

California

City

SAN JOSE

Population served

176,266

Primary source

SWP

Score history

▼ 12 points — the score moved from 100 to 88 on Jun 18, 2026, as newly published EPA data was incorporated.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 88

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

PFAS & contaminant readings

Latest detections from EPA’s UCMR5 monitoring (through Feb 2025). Levels in parts per trillion (ppt).

PFOS

Perfluorooctanesulfonic acid

5.2 ppt

limit 4 ppt

Above EPA limit · 1.3×

Violations & enforcement

No violations are on record for this system in EPA’s SDWIS/ECHO data.

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

Nitrate

6 stations · latest Nov 2023

1.03 · max 3.46 mg/l as N · 34

Copper

1 station · latest Jun 2022

3.85 · max 13 ug/L · 6

Lead

1 station · latest Jun 2022

1.2 · max 2.1 ug/L · 3

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 CA3910001 — 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.