PFAS · Guam
PFAS in Guam drinking water: EPA’s final survey results
EPA’s national PFAS survey (UCMR 5) tested 5 of the community water systems that serve homes in Guam. 3 found at least one of 29 PFAS above the laboratory reporting level, and 1 had a PFOA or PFOS sampling-location yearly average at or above EPA’s 4.0 ppt limit. Samples were collected from September 2023 to December 2025.
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
PFHxS was the compound Guam community systems found most often: 3 of 5 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in Guam the share is 60%. The largest Guam system with a detection, Gwa Northern Water System, serves 139,207 people and found 11 of the 29 compounds.
Which PFAS were found most often in Guam
Each row counts the Guam 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 |
|---|---|---|---|
| PFHxS | 3 | 5 | 60% |
| PFHxA | 2 | 5 | 40% |
| PFPeS | 2 | 5 | 40% |
| 6:2 FTS | 1 | 5 | 20% |
| 8:2 FTS | 1 | 5 | 20% |
| PFBA | 1 | 5 | 20% |
| PFBS | 1 | 5 | 20% |
| PFHpA | 1 | 5 | 20% |
| PFOA | 1 | 5 | 20% |
| PFOS | 1 | 5 | 20% |
| PFPeA | 1 | 5 | 20% |
Guam systems with the most PFAS found
The 3 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 |
|---|---|---|---|---|
| Gwa Northern Water System GU0000006 | 139,207 | 11 | 13.4 ppt at or above the MCL | 67.5 ppt at or above the MCL |
| Andersen Air Force Base Water System GU0000009 | 7,700 | 3 | — not detected above the reporting level | — not detected above the reporting level |
| U.S. Navy Water System GU0000010 | 12,780 | 1 | — not detected above the reporting level | — not detected above the reporting level |
Counties with the most systems that found PFAS
- Guam 3 of 5 surveyed systems