165 public water systems in Colorado were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.
13 of 165 systems had at least one sample above a 2024 federal limit; 99 had at least one PFAS found above the reporting level; 66 had none found above the reporting level.
A single sample above a 2024 limit is a measurement, not a violation. Compliance is judged on running yearly averages, and water systems have until 2029 to meet the limits. On 20 May 2026 EPA proposed giving qualifying systems until 2031 for PFOA and PFOS and removing the limits for PFHxS, PFNA and HFPO-DA; those proposals were not final when we last checked (5 Nov 2026). Counts are per system, not per person; population figures are available only for systems serving more than 25,000 people (about 5,294,362 people across those systems here). UCMR 5 was a one-time national monitoring programme (2023–2025). The results are a snapshot at the system's entry points or taps on the sample dates, not a continuous measurement and not a compliance record.
| System | People served | UCMR 5 result |
|---|---|---|
| Denver Denver Water Board | 1,287,000 | None detected (below the reporting level) |
| Aurora Aurora City of | 533,407 | Detected, below the 2024 limit |
| Colorado Springs Colorado Springs Utilities | 464,111 | None detected (below the reporting level) |
Pages for these are being added in stages. The data for all 165 systems is in the public dataset.
| System | People served | UCMR 5 result |
|---|---|---|
| Thornton City of Thornton City of | 226,465 | Above the 2024 limit in at least one sample |
| Westminster City of Westminster City of | 202,078 | None detected (below the reporting level) |
| Ft Collins City of Ft Collins City of | 179,901 | None detected (below the reporting level) |
| Arvada City of Arvada City of | 171,610 | None detected (below the reporting level) |
| Boulder City of Boulder City of | 166,080 | None detected (below the reporting level) |
| Greeley City of Greeley City of | 132,310 | None detected (below the reporting level) |
| Pueblo Board of Ww Pueblo Board of Ww | 114,070 | None detected (below the reporting level) |
| Castle Rock Town of Castle Rock Town of | 110,298 | None detected (below the reporting level) |
| Broomfield City and County of Broomfield City and County of | 106,153 | None detected (below the reporting level) |
| Longmont City of Longmont City of | 104,178 | None detected (below the reporting level) |
| Centennial Wsd Centennial Wsd | 103,444 | Detected, below the 2024 limit |
| Ute Wcd Ute Wcd | 92,580 | None detected (below the reporting level) |
| Loveland City of Loveland City of | 91,077 | None detected (below the reporting level) |
| Consolidated Mutual Maple Grove Consolidated Mutual Maple Grove | 81,400 | Detected, below the 2024 limit |
| Parker Wsd Parker Wsd | 75,949 | Above the 2024 limit in at least one sample |
| South Adams County Wsd South Adams County Wsd | 75,559 | None detected (below the reporting level) |
| East Cherry Creek Valley Wsd East Cherry Creek Valley Wsd | 66,130 | None detected (below the reporting level) |
| Ft Collins Loveland Wd Ft Collins Loveland Wd | 63,532 | None detected (below the reporting level) |
| Englewood City of Englewood City of | 59,904 | Detected, below the 2024 limit |
| Brighton City of Brighton City of | 56,304 | Above the 2024 limit in at least one sample |
| Eagle River Wsd Eagle River Wsd | 51,515 | None detected (below the reporting level) |
| Northglenn City of Northglenn City of | 48,927 | None detected (below the reporting level) |
| Us Department of the Army Fort Carson Us Department of the Army Fort Carson | 48,000 | None detected (below the reporting level) |
| Erie Town of Erie Town of | 47,444 | None detected (below the reporting level) |
| Golden City of Golden City of | 38,288 | None detected (below the reporting level) |