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Water system · PWSID CO0101150

THORNTON CITY OF

THORNTON, CO · ~226,465 people served

Check your exact address → THORNTON overview
65
Fair
PurityRadar safety score

PWSID

CO0101150

State

Colorado

City

THORNTON

Population served

226,465

Primary source

Surface water

Score history

▼ 35 points — the score moved from 100 to 65 on Jun 18, 2026, as newly published EPA data was incorporated.

Jun 18, 2026 · score 100 Jun 18, 2026 · score 65

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

PFOA

Perfluorooctanoic acid

6.5 ppt

limit 4 ppt

Above EPA limit · 1.6×

PFOS

Perfluorooctanesulfonic acid

4.5 ppt

limit 4 ppt

Above EPA limit · 1.1×

PFHxS

Perfluorohexanesulfonic acid

4.2 ppt

limit 10 ppt

Below EPA limit

Lithium

21,300 ppt

limit —

No federal limit

PFBA

6 ppt

limit —

No federal limit

PFHxA

5.6 ppt

limit —

No federal limit

PFPeA

5.5 ppt

limit —

No federal limit

PFBS

4.2 ppt

limit —

No federal limit

PFHpA

3.2 ppt

limit —

No federal limit

Violations & enforcement

11

Violations on record

0

Unaddressed

0

Health-based

29

Enforcement actions

From EPA ECHO (SDWIS), most recent enforcement Jun 2024. Official EPA record →

Monitoring & reporting · EPA contaminant 0300 began Nov 2023 Resolved
Monitoring & reporting · EPA contaminant 0300 began Oct 2023 Resolved
Monitoring & reporting · EPA contaminant 0300 began Sep 2023 Resolved
Monitoring & reporting · Lead & Copper Rule began Jul 2023 Resolved
Monitoring & reporting · Uranium began Apr 2022 Resolved
Monitoring & reporting · Combined radium-226/228 began Apr 2022 Resolved
Monitoring & reporting · Gross alpha began Apr 2022 Resolved
Monitoring & reporting · EPA contaminant 0300 began May 2021 Resolved
Monitoring & reporting · Lead & Copper Rule began Jul 2010 Resolved
Monitoring & reporting · EPA contaminant 2032 began Jan 2008 Resolved
Monitoring & reporting · EPA contaminant 0300 began Sep 2003 Resolved

Recent enforcement actions

  • State action · SIF Jun 2024
  • State action · SOX Jan 2024
  • State action · SOX Dec 2023
  • State action · SIE Dec 2023
  • State action · SIA Dec 2023
  • State action · SIE Nov 2023
  • State action · SIA Nov 2023
  • State action · SIE Nov 2023

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

Manganese

3 stations · latest Dec 2025

146 · max 449 ug/L · 544

Copper

2 stations · latest Dec 2025

2.9 · max 23 ug/L · 539

Lead

3 stations · latest Dec 2025

0.6 · max 11.9 ug/L · 477

Arsenic

3 stations · latest Dec 2025

0.9 · max 2.1 ug/L · 276

Fluoride

3 stations · latest Dec 2025

0.74 · max 0.98 mg/L · 275

Nitrate

2 stations · latest Dec 2024

3.36 · max 7.09 mg/L · 167

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 CO0101150 — 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.