Colorado water quality by city

By Daryna Klochko · Data checked Oct 15, 2026
Short answer

We cover 4 Colorado cities so far: Aurora, Boulder, Colorado Springs and Denver. Statewide, EPA’s UCMR 5 testing covered 165 water systems. Of these, 39 had at least one PFAS detected, and 15 had a PFOA or PFOS sample at or above 4.0 ppt, the level of the federal limit.

Systems tested165UCMR 5 · 72 large systems
Any PFAS detected3924% of systems tested
PFOA or PFOS ≥ 4 ppt15At least one sample, 2023–2025
Cities covered4Pages with full data

A single sample at or above 4.0 ppt is not a violation. The PFOA and PFOS limits apply to a running annual average, and utilities must comply from 2029. City numbers describe the water system, not your tap.

Colorado cities

Listed A–Z. We don’t rank cities: utilities sample in different years and at different points.

Aurora Water · 533,407 people

Aurora

Lead · 90th pct4.7 ppb PFAS · UCMR 5No PFOA/PFOS; 4 other PFAS HardnessNot reported EPA violations · 10 yrsNone City of Boulder · 166,080 people

Boulder

Lead · 90th pct2 ppb PFAS · UCMR 5Not detected HardnessNot reported EPA violations · 10 yrs6 (2 health-based) Colorado Springs Utilities · 464,111 people

Colorado Springs

Lead · 90th pct5.7 ppb PFAS · UCMR 5Not detected HardnessNot reported EPA violations · 10 yrs2 (0 health-based) Denver Water · 1,287,000 people

Denver

Lead · 90th pct3.6 ppb PFAS · UCMR 5Not detected Hardness105 mg/L EPA violations · 10 yrs35 (0 health-based)

Find your water system by ZIP

A ZIP code can be served by more than one system. Your water bill names yours.

Hardness in Colorado cities

Denver
105 mg/L (6.1 gpg)
Average, moderately hard; range 55–124 mg/L

Classes: USGS. 1 gpg = 17.1 mg/L as calcium carbonate. City figures come from each utility’s report. No hardness figure in our sources for Aurora, Boulder, Colorado Springs.

PFAS testing in Colorado

Between 2023 and 2025, EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5) had 165 Colorado public water systems test for 29 PFAS and lithium. 39 systems (24%) reported at least one PFAS at or above the reporting level. 15 had at least one PFOA or PFOS sample at or above 4.0 ppt, the level of the federal limit.

Source: EPA UCMR 5 final occurrence data (Aug 2026 release). Counts exclude lithium.

PFAS testing in neighboring states: Kansas, Nebraska, New Mexico, Oklahoma, Utah and Wyoming.

Sources

EPA UCMR 5 occurrence dataepa.gov EPA: find your utility’s water quality reportepa.gov How we researchMethod