PFAS · Idaho
PFAS in Idaho drinking water: EPA’s final survey results
EPA’s national PFAS survey (UCMR 5) tested 61 of the community water systems that serve homes in Idaho. 9 found at least one of 29 PFAS above the laboratory reporting level, and 2 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 March 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 Idaho community systems found most often: 7 of 61 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in Idaho the share is 15%. The largest Idaho system with a detection, Meridian Water Dept, serves 147,340 people and found 2 of the 29 compounds.
Which PFAS were found most often in Idaho
Each row counts the Idaho 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 | 7 | 61 | 11% |
| PFHxA | 6 | 61 | 10% |
| PFBS | 5 | 61 | 8% |
| PFHxS | 4 | 61 | 7% |
| PFOS | 3 | 61 | 5% |
| PFNA | 2 | 61 | 3% |
| PFOA | 1 | 61 | 2% |
| PFPeS | 1 | 61 | 2% |
Idaho systems with the most PFAS found
The 9 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 |
|---|---|---|---|---|
| Garden City Water and Sewer System ID4010066 | 12,500 | 7 | — not detected above the reporting level | 25.5 ppt at or above the MCL |
| Capitol Water Corp ID4010022 | 9,000 | 7 | 5.8 ppt at or above the MCL | 9.5 ppt at or above the MCL |
| Mountain Home Air Force Base ID4200054 | 7,500 | 4 | — not detected above the reporting level | — not detected above the reporting level |
| Lewiston City of ID2350014 | 15,001 | 3 | — not detected above the reporting level | — not detected above the reporting level |
| Meridian Water Dept ID4010097 | 147,340 | 2 | — not detected above the reporting level | 2.4 ppt below the MCL |
| Rathdrum City of ID1280152 | 10,358 | 2 | — not detected above the reporting level | — not detected above the reporting level |
| Payette City of ID3380009 | 8,127 | 2 | — not detected above the reporting level | — not detected above the reporting level |
| Coeur D Alene City of ID1280053 | 54,115 | 1 | — not detected above the reporting level | — not detected above the reporting level |
| Shelley City of ID6060071 | 4,409 | 1 | — not detected above the reporting level | — not detected above the reporting level |
Counties with the most systems that found PFAS
- Ada County 3 of 8 surveyed systems
- Kootenai County 2 of 8 surveyed systems
- Nez Perce County 1 of 2 surveyed systems
- Bingham County 1 of 4 surveyed systems
- Elmore County 1 of 2 surveyed systems
- Payette County 1 of 2 surveyed systems