PFAS · Hawaii

PFAS in Hawaii drinking water: EPA’s final survey results

EPA’s national PFAS survey (UCMR 5) tested 44 of the community water systems that serve homes in Hawaii. 2 found at least one of 29 PFAS above the laboratory reporting level, and 0 had a PFOA or PFOS sampling-location yearly average at or above EPA’s 4.0 ppt limit. Samples were collected from January 2023 to December 2025.

In focus5%of surveyed systems found PFAS

Public records. Clearer context.

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

Hawaii community systems in EPA’s survey

serving about 1,455,539 people

found at least one PFAS

5% of surveyed systems; about 848,868 people served

PFOA or PFOS yearly average at or above the MCL

compared the way EPA does: the average of a complete sampling set

lithium at or above EPA’s health reference level

lithium was part of the same survey

PFHxS was the compound Hawaii community systems found most often: 1 of 44 tested systems measured it above the reporting level. Across the country, 35% of surveyed community systems found at least one PFAS; in Hawaii the share is 5%. The largest Hawaii system with a detection, Hnl-Windward-Pearl Harbor, serves 631,389 people and found 1 of the 29 compounds.

Which PFAS were found most often in Hawaii

Each row counts the Hawaii 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	1	44	2%
PFPeA	1	44	2%

Hawaii systems with the most PFAS found

The 2 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
Hnl-Windward-Pearl Harbor HI0000331	631,389	1	— not detected above the reporting level	— not detected above the reporting level
Waipahu-Ewa-Waianae HI0000335	217,479	1	— not detected above the reporting level	— not detected above the reporting level

Counties with the most systems that found PFAS

Honolulu County 2 of 18 surveyed systems

How to read these numbers

UCMR 5 asked every community and non-transient non-community water system serving 3,300 or more people, and a sample of smaller ones, to test for 29 PFAS and lithium. EPA published the final data in August 2026; its samples were collected from January 2023 to June 2026. A system that was not in the survey has no result here; that is not the same as having no PFAS.

UCMR 5 is a one-time national monitoring survey. Its results do not indicate compliance or non-compliance with the PFAS Maximum Contaminant Levels, which are enforced on running annual averages and take effect in 2029 (EPA has proposed allowing extensions to 2031). A single result above a limit on this page is a measurement, not a violation.

See how to read UCMR 5 results and our methodology for how systems are matched to places.

After Hawaii’s PFAS results

Find your system. Then read its report.

State recordsAll Hawaii water recordsCounties, ZIP reports, lead results and violations for the whole state.FiltersChoosing a PFAS filterHow to check a filter’s certified PFAS reduction before you buy.Your utilityFind your annual water reportYour utility’s Consumer Confidence Report will list its own PFAS results and any treatment plans.

County pages

Hawaii water records

Sources

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. Database prepared 2026-09-03.