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Water system · PWSID CA5010010

MODESTO, CITY OF

MODESTO, CA · ~218,771 people served

Check your exact address → MODESTO overview
77
Good
PurityRadar safety score

PWSID

CA5010010

State

California

City

MODESTO

Population served

218,771

Primary source

SWP

Score history

▼ 23 points — the score moved from 100 to 77 on Jun 18, 2026, as newly published EPA data was incorporated.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 77

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 Sep 2024). Levels in parts per trillion (ppt).

PFOS

Perfluorooctanesulfonic acid

4.6 ppt

limit 4 ppt

Above EPA limit · 1.1×

PFOA

Perfluorooctanoic acid

4.1 ppt

limit 4 ppt

Above EPA limit · 1.0×

PFHxS

Perfluorohexanesulfonic acid

6.9 ppt

limit 10 ppt

Near EPA limit

Lithium

12,000 ppt

limit —

No federal limit

PFPeA

4.6 ppt

limit —

No federal limit

PFHxA

3.9 ppt

limit —

No federal limit

PFHpA

3.6 ppt

limit —

No federal limit

PFBS

3.4 ppt

limit —

No federal limit

Violations & enforcement

14

Violations on record

0

Unaddressed

12

Health-based

16

Enforcement actions

From EPA ECHO (SDWIS), most recent enforcement Sep 2013. Official EPA record →

Max contaminant level (MCL) · Nitrate health-based began Aug 2013 Resolved
Max contaminant level (MCL) · Nitrate health-based began Mar 2007 Resolved
Monitoring & reporting · Total coliform began Jan 2001 Resolved
Max contaminant level (MCL) · Total coliform health-based began Feb 1996 Resolved
Max contaminant level (MCL) · Total coliform health-based began Sep 1995 Resolved
Max contaminant level (MCL) · Total coliform health-based began May 1995 Resolved
Max contaminant level (MCL) · Total coliform health-based began Oct 1994 Resolved
Max contaminant level (MCL) · Total coliform health-based began Aug 1994 Resolved
Max contaminant level (MCL) · Total coliform health-based began Jul 1994 Resolved
Max contaminant level (MCL) · Combined radium-226/228 health-based began Nov 1993 Resolved
Monitoring & reporting · Total coliform began Nov 1993 Resolved
Max contaminant level (MCL) · Total coliform health-based began Jul 1993 Resolved

Recent enforcement actions

  • State action · SOX Sep 2013
  • State action · SFL Sep 2013
  • State action · SFL Jul 2010
  • State action · SOX Apr 2007
  • State action · SFL Mar 2007
  • State action · SOX Feb 2001
  • State action · SOX Oct 1997
  • State action · SOX May 1996

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

3 stations · latest Apr 2021

4.98 · max 6.4 mg/l as N · 6

Arsenic

3 stations · latest Apr 2021

5.9 · max 8.9 ug/l · 3

Copper

3 stations · latest Apr 2021

1.1 · max 1.3 ug/l · 3

Fluoride

3 stations · latest Apr 2021

0.09 · max 0.13 mg/l · 3

Uranium

3 stations · latest Apr 2021

15.5 · max 23.2 ug/l · 3

Lead

2 stations · latest Apr 2021

0.314 · max 0.514 ug/l · 2

Atrazine

1 station · latest Apr 2021

0.007 · max 0.007 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 CA5010010 — 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.