TapSafetyReport
A83/100

THORNTON CITY OF — Water Quality Report 2026

Serving 226,465 people · Colorado

Water Source
Surface Water
County
—
System ID
CO0101150
Violations
11

Contaminant Test Results

2 contaminants above EPA health goals
ContaminantDetectedLimit (MCL)Status
chlorate
820.00 µg/L—Above Goal
Lead (90th percentile)
0.002 mg/L0.015 mg/LAbove Goal

EPA Violation History

8

Violations (last 5yr)

0

Unresolved

0

Health-Related

TIER 3Resolved

Missed required monitoring deadline

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: November 1, 2023 – November 30, 2023Rule: Surface Water Treatment RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Missed required monitoring deadline

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: October 1, 2023 – October 31, 2023Rule: Surface Water Treatment RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Missed required monitoring deadline

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: September 1, 2023 – September 30, 2023Rule: Surface Water Treatment RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Failed to issue ongoing public notification

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: July 1, 2023 – December 29, 2023Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2022 – June 30, 2022Enforcement: Resolving — corrective action underway
TIER 3Resolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2022 – June 30, 2022Enforcement: Resolving — corrective action underway
TIER 3Resolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2022 – June 30, 2022Enforcement: Resolving — corrective action underway
TIER 3Resolved

Missed required monitoring deadline

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: May 1, 2021 – May 31, 2021Rule: Surface Water Treatment RuleEnforcement: Resolving — corrective action underway

Understanding violation severity

Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.

Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly

Frequently Asked Questions About THORNTON CITY OF

Is THORNTON CITY OF water safe to drink?

THORNTON CITY OF water receives a grade of A (83/100), which is considered excellent. Out of 76 contaminants tested, none exceed EPA legal limits. 2 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.

What contaminants has THORNTON CITY OF detected?

76 contaminants were tested in THORNTON CITY OF's water. Notable contaminants include Lead (90th percentile), chlorate. No contaminants exceed EPA legal limits. 2 exceed EPA health goals (MCLGs).

Does THORNTON CITY OF have any EPA violations?

Yes, THORNTON CITY OF has 11 EPA violation(s) on record, with the most recent in 2023. Violation types include MR.

How many people does THORNTON CITY OF serve?

THORNTON CITY OF serves approximately 226,465 people, Colorado.

What type of water does THORNTON CITY OF provide?

THORNTON CITY OF sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is CO0101150.

How does THORNTON CITY OF compare to other utilities in Colorado?

THORNTON CITY OF scores 83/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our Colorado state page for a full comparison of water systems.