States › Colorado

Colorado Tap Water Quality 2026

EPA drinking water data for 407 cities across Colorado — covering lead levels, violation history, and compliance status.

Systems tracked: 348 Cities covered: 407 Updated: 2026 Q2
B

Colorado earns a B for overall water quality

407 communities across 64 counties and 348 water systems. 98.0% have no open violations.

Median lead where detected: 2.00 ppb
28.2% of systems report lead as not detected — a state filing convention, not a water quality measure
PFAS tested at 37.6% of communities; 4 above the federal limit
Lead reported for 99.3% of communities
98.0% of communities have no open violations
Water Systems
348
Active community systems
Median Lead Level
2 ppb
13% of EPA action level
Fully Compliant
98%
of systems — no active violations
How we grade states Grades are based on actual EPA enforcement data — MCL violations and lead levels measured against the 15 ppb federal action level. We do not use MCLG-based detections, which are aspirational zero-tolerance goals that would make nearly every state look dangerous. Read our full methodology →

Best & Worst Cities in Colorado

✓ Cleanest Water
West Pleasant View
Jefferson County
0.0 ppb A
Aurora
Arapahoe County
2.5 ppb A
Longmont
Boulder County
1.6 ppb A
Fountain
El Paso County
4.4 ppb A
Golden
Jefferson County
0.0 ppb A
Durango
La Plata County
3.1 ppb A
⚠ Needs Attention
Colorado City
Pueblo County
3.0 ppb F
Manzanola
Otero County
0.0 ppb F
Hasty
Bent County
10.0 ppb F
Walsenburg
Huerfano County
5.0 ppb D
Brighton
Adams County
2.0 ppb D
Lochbuie
Weld County
2.0 ppb D

Water Quality by County

64 of 64
Sort:
CountySystemsLead LevelViolationsGrade
Weld County 28 2.6 ppb 0 B
Douglas County 21 2.0 ppb 0 B
Boulder County 20 2.0 ppb 0 B
Jefferson County 20 3.1 ppb 0 B
Arapahoe County 19 4.1 ppb 0 B
El Paso County 19 3.5 ppb 0 B
Adams County 16 2.0 ppb 0 B
Garfield County 11 1.7 ppb 0 A
Mesa County 10 1.4 ppb 0 A
Eagle County 10 2.0 ppb 0 B

About Colorado Drinking Water

Colorado is served by 348 community water systems covering 407 communities across 64 counties. 98.0% have no open violation on record.

Lead was detected in 290 communities, with a median of 2.00 ppb — 13% of the federal action level. A further 114 reported none detected. That share is a state reporting convention rather than a measure of water quality, so it is stated separately rather than averaged in.

PFAS has been tested at 37.6% of communities here, and 4 are above the limits EPA set in 2024. Coverage matters: states that test more find more, so this figure is not comparable with a state that has tested less.

Frequently Asked Questions

Is Colorado tap water safe to drink? ▼
98.0% of communities have no open violation on record. 4 have PFAS above the federal limit set in 2024, which is the main open concern.
Does Colorado have a lead problem? ▼
5 water systems report a 90th-percentile lead result at or above the 15 ppb action level. The action level is a treatment trigger, not a legal maximum, and 114 communities report no detection at all.
How complete is the data for Colorado? ▼
Lead results are reported for 99.3% of communities and PFAS for 37.6%. Where a figure is missing it is shown as not reported rather than assumed safe.
How does Colorado compare with other states? ▼
We do not rank states against each other. Lead reporting completeness ranges from under 20% to 100% depending on the state, so a national ranking would compare filing practice rather than water quality.