Is Tap Water Safe to Drink in Honolulu?
Yes, tap water in Honolulu is safe to drink and is some of the best municipal water in the United States. It's rainwater naturally filtered for decades through volcanic rock into underground basal aquifers, needing only light disinfection.
Water Source
The Honolulu Board of Water Supply pumps from basal aquifers beneath Oahu — rainfall that has percolated through hundreds of feet of volcanic rock over roughly 25 years, emerging so clean it requires only minimal chlorination and no conventional filtration.
EPA Compliance Status
Meets all federal Safe Drinking Water Act standards. The 2021 Red Hill fuel leak contaminated the U.S. Navy's separate water system and prompted the Board of Water Supply to shut its nearby Halawa shaft as a precaution; the civilian supply itself remained within standards, and Red Hill's defueling was completed in 2024.
Notable Contaminants & Context
- •No significant contaminants in the delivered supply; the volcanic aquifer acts as a natural filter
- •The Red Hill fuel facility sat just 100 feet above the aquifer; its 2021 jet fuel leak sickened military families on the Navy's system and led to the facility's permanent shutdown — the civilian BWS supply was not found contaminated
- •Chlorination is minimal by mainland standards, so chlorine taste is faint
Water Quality Data
Key contaminants detected vs. regulatory limits. All values from the most recent published report — Source: Honolulu Board of Water Supply 2024 CCR.
| Contaminant | Detected | Limit | Status |
|---|---|---|---|
| Chlorine (total) | 0.6 mg/L | 4.0 mg/L | ✓ |
| Fluoride | 0.71 mg/L | 4.0 mg/L | ✓ |
| Lead (90th percentile) | 1.3 µg/L | 15.0 µg/L | ✓ |
| Nitrate (as N) | 2.8 mg/L | 10.0 mg/L | ✓ |
| TTHM (Total Trihalomethanes) | 9.4 µg/L | 80.0 µg/L | ✓ |
| HAA5 (Haloacetic Acids) | 6.1 µg/L | 60.0 µg/L | ✓ |
✓ = below limit ⚠ = above health goal ✗ = exceeds guideline
How It Compares
Honolulu's naturally filtered aquifer water rivals protected-watershed systems like Boston's or Portland's, and many visitors find it tastes better than mainland water because mineral balance is good and disinfectant levels are low.
Tips
- •Drink it straight — bottled water is unnecessary on Oahu's municipal supply
- •The Board of Water Supply publishes water quality by aquifer district
- •If you're on the Navy's Joint Base system, that's a separate supply with its own post-Red Hill monitoring
Frequently Asked Questions
Sources & References
The safety rating and guidance on this page draw on the following sources. See our full methodology.
- •US EPA Safe Drinking Water Act regulations
- •EWG Tap Water Database
- •The utility's most recent Consumer Confidence Report (CCR)
- •WHO Guidelines for Drinking-water Quality