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Water system · PWSID CA3910012

CITY OF STOCKTON

STOCKTON, CA · ~191,302 people served

Check your exact address → STOCKTON overview
87
Excellent
PurityRadar safety score

PWSID

CA3910012

State

California

City

STOCKTON

Population served

191,302

Primary source

Surface water

Score history

▼ 13 points — the score moved from 100 to 87 on Jun 18, 2026, as newly published EPA data was incorporated.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 87

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 2023). Levels in parts per trillion (ppt).

PFOS

Perfluorooctanesulfonic acid

4.2 ppt

limit 4 ppt

Above EPA limit · 1.0×

Violations & enforcement

9

Violations on record

0

Unaddressed

5

Health-based

21

Enforcement actions

From EPA ECHO (SDWIS), most recent enforcement Sep 2025. Official EPA record →

Monitoring & reporting · Nitrate began Jan 2024 Resolved
Max contaminant level (MCL) · Total trihalomethanes (TTHM) health-based began Apr 2023 Resolved
Max contaminant level (MCL) · Total trihalomethanes (TTHM) health-based began Jan 2023 Resolved
Monitoring & reporting · Lead & Copper Rule began Oct 2021 Resolved
Treatment technique · EPA contaminant 0200 health-based began Mar 2016 Resolved
Max contaminant level (MCL) · Total trihalomethanes (TTHM) health-based began Jan 2013 Resolved
Other · Total coliform began Nov 2005 Resolved
Other · EPA contaminant 7000 began Jul 2001 Resolved
Max contaminant level (MCL) · Total coliform health-based began Dec 1999 Resolved

Recent enforcement actions

  • State action · SOX Sep 2025
  • State action · SFL Mar 2025
  • State action · SOX Jan 2025
  • State action · SOX Jun 2024
  • State action · SFL Oct 2023
  • State action · SFL Apr 2023
  • State action · SOX Jul 2019
  • State action · SOX Mar 2017

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

2 stations · latest Nov 2023

1.24 · max 3.76 mg/l as N · 34

Copper

2 stations · latest Sep 2021

1.4 · max 1.8 ug/l · 11

Atrazine

1 station · latest Feb 2020

0 · max 0 ng/L · 3

Arsenic

1 station · latest Mar 2020

5.8 · max 5.8 ug/l · 1

Fluoride

1 station · latest Mar 2020

0.08 · max 0.08 mg/l · 1

Lead

1 station · latest Mar 2020

1.21 · max 1.21 ug/l · 1

Manganese

1 station · latest Mar 2020

28.7 · max 28.7 ug/l · 1

Uranium

1 station · latest Mar 2020

7.74 · max 7.74 ug/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 CA3910012 — 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.