PFAS in Guam drinking water
EPA's final UCMR 5 data covers 5 public water systems in Guam, serving about 186,886 people. PFAS turned up in 3 of them (60%). 1 averaged above at least one EPA limit at a sampling point, affecting about 139,207 people.
Highest PFOA and PFOS averages among systems serving 1,000 or more: Gwa Northern Water System (13.4 / 67.5 ppt).
Every tested system in Guam
Largest first. PFOA and PFOS columns show the average at each system's worst sampling point; EPA's limit for each is 4 ppt. Filter by name:
| Water system | People | PFOA | PFOS | PFAS found | Result |
|---|---|---|---|---|---|
| Gwa Northern Water System · Mangilao | 139,207 | 13.4 | 67.5 | 11 | Above limit |
| Gwa Central Water System · Mangilao | 21,398 | - | - | 0 | None found |
| U.s. Navy Water System · Fp | 12,780 | - | - | 1 | Below limits |
| Andersen Air Force Base Water System · Apo Ap | 7,700 | - | - | 3 | Below limits |
| Gwa Southern Water System · Mangilao | 5,801 | - | - | 0 | None found |
On a private well in Guam?
EPA's program only covers public systems. Private wells are never part of UCMR 5, so the only way to know is to test. Our well testing guide covers which lab tests to order, and the best well water systems covers what to install once you have results.
Cite this page
Well & Tap. "PFAS in Guam drinking water: results for 5 systems." Data: U.S. EPA UCMR 5, final release August 2026. https://wellandtap.com/pfas/guam/
Source: EPA UCMR 5 final occurrence data (August 2026); population from EPA SDWIS. Method.