PFAS · Colorado
PFAS in Colorado drinking water: EPA’s final survey results
EPA’s national PFAS survey (UCMR 5) tested 158 of the community water systems that serve homes in Colorado. 37 found at least one of 29 PFAS above the laboratory reporting level, and 4 had a PFOA or PFOS sampling-location yearly average at or above EPA’s 4.0 ppt limit. Samples were collected from January 2023 to May 2026.
Data as of EPA UCMR 5 final release, August 2026 (file dated Aug 28, 2026) · EPA SDWIS 2026Q2 (file dated Jul 9, 2026). How we build these pages
PFPeA was the compound Colorado community systems found most often: 25 of 158 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in Colorado the share is 23%. The largest Colorado system with a detection, Aurora City of, serves 533,407 people and found 4 of the 29 compounds.
Which PFAS were found most often in Colorado
Each row counts the Colorado community water systems where that compound was measured above the reporting level at least once. A detection is a measurement, not a violation: most of these compounds have no federal limit.
| Compound | Systems where found | Systems tested | Share |
|---|---|---|---|
| PFPeA | 25 | 158 | 16% |
| PFBA | 24 | 158 | 15% |
| PFBS | 24 | 158 | 15% |
| PFHxA | 24 | 158 | 15% |
| PFOA | 11 | 158 | 7% |
| PFHxS | 10 | 158 | 6% |
| PFOS | 9 | 158 | 6% |
| PFHpA | 4 | 158 | 3% |
| PFPeS | 1 | 158 | 1% |
Colorado systems with the most PFAS found
The 10 surveyed community water systems that found the most different PFAS, with PFOA and PFOS compared to EPA’s 4.0 ppt limits on the yearly average at the highest sampling location. Larger systems come first when counts tie.
| Water system | People served | PFAS found (of 29) | PFOA | PFOS |
|---|---|---|---|---|
| Thornton City of CO0101150 | 226,465 | 8 | 3.4 ppt below the MCL | 2.4 ppt below the MCL |
| Widefield WSD CO0121900 | 27,640 | 8 | 10.3 ppt at or above the MCL | 11.9 ppt at or above the MCL |
| Brighton City of CO0101025 | 56,304 | 7 | 2.5 ppt below the MCL | 8.0 ppt at or above the MCL |
| Snake River WD CO0159105 | 9,900 | 7 | 2.9 ppt below the MCL | 17.5 ppt at or above the MCL |
| Stonegate Md CO0118076 | 15,295 | 6 | 1.4 ppt below the MCL | 1.3 ppt below the MCL |
| Todd Creek Village Md CO0101157 | 7,363 | 6 | — not detected above the reporting level | 5.4 ppt at or above the MCL |
| Parker WSD CO0118040 | 75,949 | 5 | 1.2 ppt below the MCL | — not detected above the reporting level |
| Englewood City of CO0103045 | 57,332 | 5 | 1.0 ppt below the MCL | — not detected above the reporting level |
| Arapahoe Cnty Wwwa CO0203002 | 31,000 | 5 | 2.3 ppt below the MCL | — not detected above the reporting level |
| Cottonwood WSD CO0118020 | 10,867 | 5 | 2.0 ppt below the MCL | — not detected above the reporting level |
Counties with the most systems that found PFAS
- Douglas County 8 of 12 surveyed systems
- El Paso County 6 of 17 surveyed systems
- Arapahoe County 5 of 5 surveyed systems
- Adams County 4 of 7 surveyed systems
- Jefferson County 2 of 8 surveyed systems
- Summit County 2 of 5 surveyed systems
- Larimer County 1 of 12 surveyed systems
- Weld County 1 of 15 surveyed systems