State profile · EPA SDWIS + UCMR5
Hawaii Drinking Water Quality
137 public water systems serve 1,520,931 people across Hawaii, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 137
- Water systems
- 5,234
- Total violations
- 80.3%
- Systems w/ a violation
- 4.4%
- PFAS detection rate
The verdict
Across Hawaii, 110 of 137 water systems (80.3%) carry at least one EPA violation, and 2 of 45 UCMR5-tested systems show PFAS.
- 5,234
- Total EPA violations on record
- 44%
- Health-based (MCL / treatment)
- 80.3%
- Systems with ≥1 violation
- 4.4%
- UCMR5 PFAS detection rate
Violation Composition
How Hawaii's 5,234 violations break down by type, per EPA SDWIS classification.
| Metric | Value | Share |
|---|---|---|
| Public water systems | 137 | - |
| Population served | 1,520,931 | - |
| Total violations | 5,234 | 100% |
| Health-based violations | 2,289 | 43.7% |
| Systems with violations | 110 | 80.3% |
| PFAS detection rate | 2 of 45 | 4.4% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Most Violations
Counties in Hawaii
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Hawaii? ▼
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Has PFAS been found in Hawaii drinking water? ▼
What is the violation rate for Hawaii water systems? ▼
Where does this Hawaii water data come from? ▼
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.