All 28 systems had enough required samples to calculate a yearly average. 1 had at least one yearly average at or above a study benchmark; 27 did not.
EPA-based study benchmark: the unrounded cutoff this research uses to reproduce EPA’s January 2026 technical-assistance classification around the April 2024 federal levels. It is not a current standard or compliance finding and cannot determine household exposure or health risk.
Find your water system
ZIP codes are used only to route visitors to public water systems that reported serving them. Confirm the actual provider using a water bill or utility record.
System counts in Wyoming
Each count shows how many included water systems had a yearly average at or above the named study benchmark.
| Study benchmark | Systems at or above benchmark | Water systems included | Percent |
|---|---|---|---|
| PFOA: 4.05 ppt study benchmark (reproduces EPA classification around 4 ppt) | 0 | 28 | 0.0% |
| PFOS: 4.05 ppt study benchmark (reproduces EPA classification around 4 ppt) | 0 | 28 | 0.0% |
| PFHxS: 15 ppt study benchmark (reproduces EPA classification around 10 ppt) | 1 | 28 | 3.6% |
| PFNA: 15 ppt study benchmark (reproduces EPA classification around 10 ppt) | 0 | 28 | 0.0% |
| HFPO-DA: 15 ppt study benchmark (reproduces EPA classification around 10 ppt) | 0 | 28 | 0.0% |
| Hazard Index: 1.5 study benchmark with at least two detected components (reproduces EPA classification around 1) | 1 | 28 | 3.6% |
Community water systems with complete monitoring
“Complete monitoring” means at least one sampling location had all required samples needed for a yearly average. Each PWSID appears once, preventing double counting across ZIP associations.
| Public water system | PWSID | Population served | Primary source | Sampling locations | Study benchmark result |
|---|---|---|---|---|---|
| CASPER, CITY OF | WY5601415 | 59,000 | Surface water purchased | 2 | Below all study benchmarks |
| CHEYENNE BOARD OF PUBLIC UTILITIES | WY5600011 | 64,165 | Surface water | 2 | Below all study benchmarks |
| DOUGLAS, CITY OF | WY5600137 | 6,400 | Surface water | 3 | Below all study benchmarks |
| EVANSTON, CITY OF | WY5600150 | 11,727 | Surface water | 1 | Below all study benchmarks |
| FIRST FIKE SUBDIVISION | WY5600194 | 150 | Ground water | 2 | Below all study benchmarks |
| FORT WASHAKIE | 085690003 | 2,620 | Surface water | 4 | Below all study benchmarks |
| GILLETTE, CITY OF | WY5600019 | 32,222 | Ground water | 2 | Below all study benchmarks |
| GREEN RIVER, CITY OF | WY5601181 | 10,500 | Surface water purchased | 1 | Below all study benchmarks |
| GTNP-COLTER BAY VILLAGE | WY5680095 | 4,514 | Ground water | 1 | Below all study benchmarks |
| HIGH MEADOW RANCH | WY5601569 | 580 | Ground water | 1 | Below all study benchmarks |
| JACKSON, TOWN OF | WY5600213 | 24,760 | Ground water | 3 | Below all study benchmarks |
| LANDER, CITY OF | WY5600176 | 7,615 | Surface water | 1 | Below all study benchmarks |
| LARAMIE, CITY OF | WY5600029 | 32,395 | Surface water | 4 | Below all study benchmarks |
| LOVELL, TOWN OF | WY5600031 | 2,250 | Surface water purchased | 1 | Below all study benchmarks |
| MILLS, TOWN OF | WY5600036 | 4,050 | Groundwater under influence of surface water | 1 | Below all study benchmarks |
| NEWCASTLE, CITY OF | WY5600256 | 3,595 | Ground water | 5 | Below all study benchmarks |
| NORTHWEST RURAL WATER DISTRICT, WY | WY5601254 | 7,330 | Surface water purchased | 1 | Below all study benchmarks |
| POWELL, CITY OF | WY5600042 | 6,310 | Surface water purchased | 1 | Below all study benchmarks |
| RAWLINS WATER SUPPLY, CITY OF | WY5600045 | 9,006 | Surface water | 1 | Below all study benchmarks |
| RIVERTON, CITY OF | WY5600047 | 10,330 | Surface water | 15 | At or above a study benchmark |
| ROCK SPRINGS, CITY OF | WY5601182 | 24,000 | Surface water purchased | 1 | Below all study benchmarks |
| SHERIDAN WY, CITY OF | WY5600052 | 22,700 | Surface water | 2 | Below all study benchmarks |
| SOUTH CHEYENNE WATER & SEWER DISTRICT | WY5600239 | 10,000 | Surface water purchased | 1 | Below all study benchmarks |
| TORRINGTON MUNICIPAL WS | WY5600164 | 6,847 | Ground water | 2 | Below all study benchmarks |
| USAF F.E. WARREN AFB | WY5680122 | 5,500 | Surface water purchased | 1 | Below all study benchmarks |
| WHEATLAND, TOWN OF | WY5600187 | 3,659 | Ground water | 3 | Below all study benchmarks |
| WORLAND UTILITIES COMMISSION | WY5600197 | 4,787 | Ground water | 1 | Below all study benchmarks |
| YNP-OLD FAITHFUL | WY5680085 | 7,675 | Surface water | 1 | Below all study benchmarks |
What is included
Each active community water system with enough required samples for a yearly average is counted once, even if it is linked with several ZIP codes. This does not mean every home was tested. Private wells are excluded, and UCMR 5 did not comprehensively monitor every small system. This page does not apply Wyoming's state-specific standards or determine compliance. Use the official state or territory drinking-water program for current regulatory information.