99 public water systems in Puerto Rico were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.
28 of 99 systems had at least one sample above a 2024 federal limit; 31 had at least one PFAS found above the reporting level; 68 had none found above the reporting level.
A single sample above a 2024 limit is a measurement, not a violation. Compliance is judged on running yearly averages, and water systems have until 2029 to meet the limits. On 20 May 2026 EPA proposed giving qualifying systems until 2031 for PFOA and PFOS and removing the limits for PFHxS, PFNA and HFPO-DA; those proposals were not final when we last checked (5 Nov 2026). Counts are per system, not per person; population figures are available only for systems serving more than 25,000 people (about 2,467,148 people across those systems here). UCMR 5 was a one-time national monitoring programme (2023–2025). The results are a snapshot at the system's entry points or taps on the sample dates, not a continuous measurement and not a compliance record.
| System | People served | UCMR 5 result |
|---|---|---|
| Metropolitano (San Juan) Metropolitano | 1,084,637 | Above the 2024 limit in at least one sample |
Pages for these are being added in stages. The data for all 99 systems is in the public dataset.
| System | People served | UCMR 5 result |
|---|---|---|
| Mayaguez Mayaguez | 152,342 | None detected (below the reporting level) |
| Aguadilla Aguadilla | 124,782 | Above the 2024 limit in at least one sample |
| Ponce Urbano Ponce Urbano | 113,972 | Above the 2024 limit in at least one sample |
| Rio Blanco,Vieques,Culedra Rio Blanco,Vieques,Culedra | 79,822 | None detected (below the reporting level) |
| El Yunque El Yunque | 68,114 | None detected (below the reporting level) |
| Arecibo Urbano Arecibo Urbano | 61,626 | Above the 2024 limit in at least one sample |
| Fajardo Ceiba Fajardo Ceiba | 59,044 | None detected (below the reporting level) |
| Isabela Isabela | 49,937 | None detected (below the reporting level) |
| Caguas Norte Caguas Norte | 47,352 | Above the 2024 limit in at least one sample |
| Lajas Lajas | 47,350 | None detected (below the reporting level) |
| Santa Isabel Urbano Santa Isabel Urbano | 39,925 | Above the 2024 limit in at least one sample |
| Las Piedras Humacao Las Piedras Humacao | 38,897 | Above the 2024 limit in at least one sample |
| Dorado Urbano Dorado Urbano | 37,244 | Above the 2024 limit in at least one sample |
| Guayama Urbano Guayama Urbano | 37,076 | None detected (below the reporting level) |
| Juncos - Ceiba Sur Juncos - Ceiba Sur | 36,835 | Above the 2024 limit in at least one sample |
| Yauco Yauco | 35,639 | None detected (below the reporting level) |
| Cidra Urbano Cidra Urbano | 34,424 | Above the 2024 limit in at least one sample |
| Caguas Sur Caguas Sur | 34,261 | None detected (below the reporting level) |
| Regional Villalba Toa Vaca Regional Villalba Toa Vaca | 34,259 | None detected (below the reporting level) |
| Patillas Urbano Patillas Urbano | 32,222 | Above the 2024 limit in at least one sample |
| Maguayo Maguayo | 30,235 | None detected (below the reporting level) |
| Hatillo-Camuy Hatillo-Camuy | 28,935 | None detected (below the reporting level) |
| Quebradillas Urbano Quebradillas Urbano | 27,760 | None detected (below the reporting level) |
| Vega Baja Urbano Vega Baja Urbano | 26,935 | Above the 2024 limit in at least one sample |
| San Lorenzo Urbano San Lorenzo Urbano | 26,470 | None detected (below the reporting level) |