8 community and non-transient non-community water systems are listed for Guam in EPA SDWIS. 5 were sampled under UCMR 5; 3 of those had at least one PFAS result at or above the reporting level, and 1 had a highest single result at or above a 2024 EPA limit (PFOA or PFOS 4 ppt, or Hazard Index 1).
Guam map · Download: systems (CSV) · all results (CSV, gzip)
These are monitoring results collected under EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) at entry points, where treated water enters the distribution system; they are not tap-water samples. They are not compliance determinations: compliance with EPA's 2024 PFAS limits is judged on running annual averages of compliance monitoring, required from 2029, so a single UCMR 5 result at or above a limit is not a violation. “< MRL” means the compound was not quantified at EPA's minimum reporting level; it does not mean zero.
Sampled under UCMR 5 (5)
| System | PWSID | City | Population | Highest PFOA (ppt) | Highest PFOS (ppt) | Highest HI | Highest single result |
|---|---|---|---|---|---|---|---|
| Andersen Air Force Base Water System | GU0000009 | Apo Ap | 7,700 | <MRL | <MRL | 0.34 | Hazard Index below its limit |
| Gwa Central Water System | GU0000003 | Mangilao | 8,828 | <MRL | <MRL | 0 | No PFAS detected |
| Gwa Northern Water System | GU0000006 | Mangilao | 139,207 | 18.3 | 135 | 8.005 | PFOS ≥ 3 × its limit |
| Gwa Southern Water System | GU0000001 | Mangilao | 5,801 | <MRL | <MRL | 0 | No PFAS detected |
| U.S. Navy Water System | GU0000010 | Fpo Ap | 12,780 | <MRL | <MRL | 0.34 | Hazard Index below its limit |
Not tested under UCMR 5 (3)
UCMR 5 required monitoring by systems serving 3,300 or more people and by a representative sample of smaller systems. The systems below have no UCMR 5 results in EPA's data. Not tested is not the same as not detected: the absence of results says nothing about PFAS in their water.
| System | PWSID | Type | City | Population | Counties |
|---|---|---|---|---|---|
| Guam International Airport Authority | GU0000018 | NTNCWS | Tamuning | 138,336 | Guam |
| Guam Plaza Resort Water System | GU0000015 | NTNCWS | Tumon | 1,095 | Guam |
| Guam Regional Medical City | GU0000019 | NTNCWS | Dededo | 1,100 | Guam |