Hawaii Tap Water Quality Report
37 cities analyzed • 942,998 people served
Updated March 2026 • Data from EWG & EPA SDWIS
Most Common Contaminants in Hawaii
| Contaminant | Found In | % of Cities |
|---|---|---|
| Total trihalomethanes (TTHMs) carcinogen | 29 of 37 | 78% |
| Bromoform carcinogen | 28 of 37 | 76% |
| Nitrate carcinogen | 24 of 37 | 65% |
| Nitrate and nitrite carcinogen | 24 of 37 | 65% |
| Dibromochloromethane carcinogen | 21 of 37 | 57% |
| Haloacetic acids (HAA5) carcinogen | 16 of 37 | 43% |
| Dibromoacetic acid | 15 of 37 | 41% |
| Chromium (total) | 13 of 37 | 35% |
| Fluoride | 11 of 37 | 30% |
| Bromodichloromethane carcinogen | 11 of 37 | 30% |
City-by-City Water Quality Rankings
Ranked by number of contaminants above EWG health guidelines (most to fewest).
| # | City | Detected | Above Guidelines | Above Legal | People Served |
|---|---|---|---|---|---|
| 1 | Wailuku | 25 | 16 | 0 | 74,511 |
| 2 | Lihue | 25 | 15 | 0 | 34,854 |
| 3 | Kaneohe Bay | 26 | 12 | 0 | 16,300 |
| 4 | Holualoa | 19 | 12 | 0 | 250 |
| 5 | Honolulu | 26 | 11 | 0 | 631,389 |
| 6 | Kunia | 12 | 11 | 0 | 650 |
| 7 | Waikoloa | 15 | 10 | 0 | 12,100 |
| 8 | Makawao | 12 | 9 | 0 | 1,200 |
| 9 | Jbpph | 13 | 8 | 0 | 65,230 |
| 10 | Schofield Barracks | 12 | 8 | 0 | 37,920 |
| 11 | Maunaloa | 9 | 8 | 0 | 1,000 |
| 12 | Lanai City | 8 | 7 | 0 | 3,200 |
| 13 | Kaunakakai | 7 | 7 | 0 | 2,400 |
| 14 | Kailua Kona | 9 | 7 | 0 | 468 |
| 15 | Laie | 8 | 7 | 0 | 0 |
| 16 | Kahului | 8 | 6 | 0 | 606 |
| 17 | Pearl City | 7 | 6 | 0 | 444 |
| 18 | Kalaupapa | 6 | 6 | 0 | 110 |
| 19 | Hawaii National Park | 8 | 6 | 0 | 0 |
| 20 | Pahoa | 6 | 5 | 0 | 3,546 |
| 21 | Kailua-kona | 9 | 5 | 0 | 1,945 |
| 22 | Beverly Hills | 7 | 5 | 0 | 100 |
| 23 | Kaumakani | 6 | 4 | 0 | 1,271 |
| 24 | Kamuela | 4 | 4 | 0 | 850 |
| 25 | Hana | 4 | 4 | 0 | 816 |
| 26 | Pukalani | 7 | 4 | 0 | 32 |
| 27 | Hilo | 7 | 3 | 0 | 39,477 |
| 28 | Kapalua | 3 | 3 | 0 | 4,200 |
| 29 | Aiea | 3 | 3 | 0 | 43 |
| 30 | Wahiawa | 2 | 2 | 0 | 400 |
| 31 | Kalaheo | 3 | 2 | 0 | 260 |
| 32 | Koloa | 2 | 2 | 0 | 175 |
| 33 | Kahuku | 2 | 2 | 0 | 75 |
| 34 | Puunene | 1 | 1 | 0 | 90 |
| 35 | Princeville | 1 | 0 | 0 | 6,911 |
| 36 | Anahola | 11 | 0 | 0 | 100 |
| 37 | Pahala | 0 | 0 | 0 | 75 |
Recommended Filtration for Hawaii
Based on the most common contaminants found across Hawaii (Total trihalomethanes (TTHMs), Bromoform, Nitrate), we recommend a reverse osmosis system or high-quality carbon block filter to remove disinfection byproducts and their precursors.
Echo RO System
Removes up to 99.9% of contaminants. The gold standard for drinking water in Hawaii homes.
View RO SystemsEcho Whole-Home Filter
Protect every tap in your home from chlorine, VOCs, and disinfection byproducts.
View Whole-Home FiltersEcho Hydrogen Water Flask
Once your water is clean, supercharge it with molecular hydrogen for antioxidant and anti-inflammatory benefits.
Shop Hydrogen FlaskFrequently Asked Questions
Is Hawaii tap water safe to drink?
Water quality varies significantly across Hawaii. Of the 37 cities analyzed, the average city has 6.0 contaminants above EWG health guidelines. The best water quality was found in Princeville. We recommend checking your specific city's report for detailed information.
What city has the best water in Hawaii?
Based on our analysis, Princeville has the fewest contaminants above EWG health guidelines in Hawaii, with 0 above guideline levels.
What city has the worst water in Hawaii?
Based on our analysis, Wailuku has the most contaminants above EWG health guidelines in Hawaii, with 16 above guideline levels.
What's the best water filter for Hawaii residents?
For most Hawaii households, we recommend a reverse osmosis (RO) system for drinking water and a whole-home filter for showers and baths. The specific recommendation depends on your city's contaminant profile — check your city's report for personalized guidance.
National Water Quality Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
