Honolulu County tap water
0 of 18 water systems serving Honolulu County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 30 community water systems list this county as served; 18 serve 3,300+ people with full PFAS testing.
- 1 had a health-based violation since 2021-10-26.
Largest systems serving this county
| System | Source | People served (whole system) | PFAS above a 2024 level? | Violations since 2021-10-26 |
|---|---|---|---|---|
| Hnl-Windward-Pearl Harbor | Groundwater | 631,389 | No | 0 |
| Waipahu-Ewa-Waianae | Groundwater | 217,479 | No | 0 |
| Joint Base Pearl Harbor-Hickam | Groundwater | 65,230 | No | 0 |
| Mililani | Groundwater | 50,573 | No | 0 |
| Schofield Barracks | Groundwater | 37,920 | No | 0 |
| Wahiawa | Groundwater | 23,348 | No | 0 |
| Marine Corps Base Hawaii | Purchased groundwater | 16,300 | No | 0 |
| Waipio Heights | Groundwater | 11,516 | No | 0 |
| Waialua-Haleiwa | Groundwater | 9,996 | No | 0 |
| Fort Shafter | Groundwater | 7,067 | No | 0 |
| Nctams Eastpac | Groundwater | 6,470 | No | 0 |
| Aliamanu | Purchased groundwater | 6,406 | No | 0 |
Which one is yours? A county usually has several utilities. Your bill or your utility's annual water-quality report names yours. Population is for the whole system, which can cross county lines.
Not medical or legal advice. UCMR 5 results are screening data, not compliance determinations.
Sources and freshness
Public-water-system facts, violations and lead/copper results: EPA ECHO SDWA download (SDWIS snapshot 2026-10-13). PFAS and lithium results: EPA UCMR 5 final data (sampling 2023–2025). Both are U.S. government works, downloaded 2026-10-26. Numbers are computed by the published method; the same fields are in the open data files.