45 public water systems in Hawaii were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.
0 of 45 systems had at least one sample above a 2024 federal limit; 1 had at least one PFAS found above the reporting level; 44 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 1,210,882 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 |
|---|---|---|
| Hnl-Windward-Pearl Harbor Hnl-Windward-Pearl Harbor | 631,389 | Detected, below the 2024 limit |
Pages for these are being added in stages. The data for all 45 systems is in the public dataset.
| System | People served | UCMR 5 result |
|---|---|---|
| Waipahu-Ewa-Waianae Waipahu-Ewa-Waianae | 217,479 | None detected (below the reporting level) |
| Wailuku Wailuku | 74,511 | None detected (below the reporting level) |
| Joint Base Pearl Harbor-Hickam Joint Base Pearl Harbor-Hickam | 65,230 | None detected (below the reporting level) |
| Mililani Mililani | 50,573 | None detected (below the reporting level) |
| Hilo Hilo | 39,477 | None detected (below the reporting level) |
| Schofield Barracks Schofield Barracks | 37,920 | None detected (below the reporting level) |
| Lihue-Kapaa Lihue-Kapaa | 34,854 | None detected (below the reporting level) |
| Makawao Makawao | 29,868 | None detected (below the reporting level) |
| North Kona North Kona | 29,581 | None detected (below the reporting level) |
| Olaa-Mountain View Olaa-Mountain View | — | None detected (below the reporting level) |
| Hawaiian Beaches Hawaiian Beaches | — | None detected (below the reporting level) |
| North Kohala North Kohala | — | None detected (below the reporting level) |
| South Kohala South Kohala | — | None detected (below the reporting level) |
| South Kona South Kona | — | None detected (below the reporting level) |
| Waikoloa Waikoloa | — | None detected (below the reporting level) |
| Hawaii Volcanoes Nat.Park Hawaii Volcanoes Nat.Park | — | None detected (below the reporting level) |
| Kohala Ranch Water Co. Kohala Ranch Water Co. | — | None detected (below the reporting level) |
| Haina Haina | — | None detected (below the reporting level) |
| Kapalua Kapalua | — | None detected (below the reporting level) |
| Kaanapali Kaanapali | — | None detected (below the reporting level) |
| Lahaina Lahaina | — | None detected (below the reporting level) |
| Upper Kula Upper Kula | — | None detected (below the reporting level) |
| Keanae Keanae | — | None detected (below the reporting level) |
| Kaunakakai Kaunakakai | — | None detected (below the reporting level) |
| Lower Kula Lower Kula | — | None detected (below the reporting level) |