State profile · EPA SDWIS + UCMR5
Colorado Drinking Water Quality
2,193 SDWIS-listed public water systems serve 7,473,456 people across Colorado. Violation rates use that full inventory; PFAS rates use only the UCMR5-tested subset.
- 2,193
- SDWIS water systems
- 238,796
- Total violations
- 92.6%
- SDWIS systems w/ a violation
- 22.7%
- UCMR5 PFAS rate (163 tested)
The verdict
7,473,456 people served via SDWIS-listed systems - larger served population (> 5,131,439). According to EPA SDWIS population served, Colorado ranks #16 of 66 states and territories by people served through public water systems.
- #16 of 66
- Population · states corpus
- 238,796
- Total EPA violations on record
- 13%
- Health-based (MCL / treatment)
- 92.6%
- SDWIS systems with ≥1 violation
SDWIS violation % and UCMR5 PFAS % use different denominators (full inventory vs tested subset). Population ordinal uses SDWIS population served.
Colorado standing, mid SDWIS violation-rate third
Colorado lands in the middle third by violation rate (92.6%) - enough flagged systems for peer comparisons without matching the densest ledgers. Population served is large (7,473,456; larger served population (> 5,131,439)), so household exposure scale sits behind inventory and rate. Health-based share is 13% - a material slice is exposure-relevant, with the rest monitoring or reporting. UCMR5 PFAS detection is 22.7% on the tested subset (mid UCMR5 detection (≤ 35.3%)) - a different denominator from the SDWIS violation rate. Systems listed below are ranked by population served or violation count; pair rate with inventory size before reading exposure scale.
Nationwide similar states
Nearest by SDWIS violation rate
Nearest by population served
Health-based share of this violation record
EPA SDWIS classifications for Colorado's 238,796 recorded violations.
Colorado vs nearest violation-rate peers
Share of SDWIS-listed systems with at least one recorded violation; peers are nearest by absolute rate distance, not a fixed top-seven list.
- CO
Colorado
92.6 % of systems
- LA
Louisiana
92.5 % of systems
- NV
Nevada
92.5 % of systems
- NC
North Carolina
92.9 % of systems
- VT
Vermont
93 % of systems
What this shows Colorado's rate is 92.6% (2,030 of 2,193 systems; middle-third rate (≤ 96.1%)). This is a comparison of recorded SDWIS violations, not a measure of current water safety.
Colorado vs all jurisdictions by SDWIS system inventory
Where this state's public water system count sits among every state and territory on PlainWater
2,193 23rd of 66 higher than 43 of 66 jurisdictions
States and territories, banded by SDWIS-listed public water system count
Each bar is a band; taller bars hold more jurisdictions. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS state aggregates · 2026-05-15
Largest Water Systems
Most Violations
Counties in Colorado
Showing top 30 of 64 counties.
Context: Check your water system · methodology · all states
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.