EPA system PR0003283 · Puerto Rico

Mayaguez: No PFAS or lithium found in EPA testing

System ID PR0003283; community water system; Puerto Rico; source: surface water; serves 152,342 people via 57,057 connections; status: active

In focus152,342people served, EPA registry

Public records. Clearer context.

Mayaguez is a local-government-owned community water system in Puerto Rico serving about 152,342 people, matched to 2 ZIP codes.

PFAS and lithium: what EPA's national survey found

EPA tested this water for 30 substances and found none of them at levels its laboratories can measure.

Between March 2025 and December 2025, EPA's UCMR 5 program tested 780 samples from 12 sampling locations for 30 contaminants (29 PFAS plus lithium). None were found above their minimum reporting levels.

Sampling-point average: mean of a location's two (ground water) or four (surface water) UCMR 5 results with non-detects counted as zero, EPA's method for comparing UCMR 5 data to the PFAS MCLs. EPA rounds to the reference value's significant digits before deciding whether an average is "greater than" an MCL (PFOA/PFOS averages count as above 4.0 ng/L only from 4.05 ng/L; lithium results count as above the 10 ppb reference only from 15 ppb). This site does not apply that rounding: "at or above" here means the measured value is numerically at or above the reference.

Utility-reported context (UCMR 5 questionnaire, aggregated across sampling events): PFAS previously found at this system: not known at 28 of 28 sampling events; potential PFAS sources nearby: not known at 28 of 28 sampling events.

Lead and copper at customer taps

In the latest completed monitoring period, ending Dec 31, 2015, 9 in 10 sampled homes had lead at or below 6 ppb, below the 15 ppb action level that triggers utility action. None of the 12 periods on record reached it.

In the most recent completed lead monitoring period, ending Dec 31, 2015, the 90th-percentile lead result at customer taps was 6 ppb, below the action level of 15 ppb (12 monitoring periods on record, none at the action level). The 90th percentile is the value that 9 in 10 sampled homes were at or below. Values are in parts per billion (ppb).

Drinking water violations since Sep 3, 2016

EPA lists 127 violations since Sep 3, 2016. 7 are health-based, meaning a contaminant or treatment rule was not met. The other 120 concern missed monitoring, reporting or public notices.

EPA's SDWIS database lists 127 violations recorded since Sep 3, 2016: 7 health-based (a contaminant above its maximum contaminant level, a disinfectant above its maximum residual level, or a required treatment technique not met), 118 for monitoring or reporting, 2 other (public notification or consumer confidence report requirements).

Sanitary surveys and site visits

Most recent state inspection: Jul 31, 2024 (sanitary survey); 1 visit since Sep 3, 2021.

What you can do about these results

ZIP codes served

Sources

Data vintage: EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.

• EPA ECHO detailed facility report
• EPA UCMR 5 Data Finder
• EPA service-area boundary: modeled, 35.1 sq mi