Manganese is worth checking in Hawaii County wells.
1 worth checking, 5 rare out of 6 health checks.
From 24 wells tested in Hawaii County since 2007; your own well needs its own test. How to read this
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 4 people 44,908 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
Radon risk (a gas from rock)
Less likely, but the EPA still says test your air.
Radon zones: EPA map
Here's how Hawaii County compares with Hawaii and the counties around it.
This one is worth checking in Hawaii County.
Manganese1 of 18 wells over
These 5 are rare in Hawaii County.
Nitrate0 of 11 wells over
Arsenic0 of 18 wells over
Uranium0 of 18 wells over
Lead0 of 17 wells over
Fluoride0 of 18 wells over
Every well needs a bacteria test every year.
No bacteria tests from Hawaii County wells are in the public data. Test every year anyway.
Iron reached staining levels in 1 of 18 tested wells, and it isn't a health risk.
Iron stains1 of 18 wells had it
Hawaii County has 24 tested wells, and the busiest decade for testing was the 2010s.
Only 3 of the 24 wells have a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Hawaii County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Hawaii County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Hawaii offers well owners
- Free testingWe didn't find a free program for all of Hawaii. Hawaii's private well page
- Certified labsHawaii's list of certified labs
- Well recordsHawaii's well record search
Here's what we know about radon and PFAS in Hawaii County.
Hawaii County is in the EPA's lowest radon zone, so radon from well water is unlikely to be a problem. Radon guide
Between 2023 and 2025 the EPA had 11 town water systems in Hawaii County test for PFAS. None found any. No well in Hawaii County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Hawaii County
Is well water in Hawaii County safe to drink?
1 of 18 wells tested in Hawaii County had manganese over the limit, about 1 in 18. Across Hawaii it's about 1 in 34. So test your own well for manganese before you count on it.
Where can I get my well tested in Hawaii County?
Use a lab Hawaii has certified for drinking water. Hawaii's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Hawaii County.
How often should I test my well in Hawaii County?
Hawaii County has no public bacteria results for wells, so follow the CDC's advice: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Hawaii County numbers come from
- People on wells: 44,908 in Hawaii County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 326 well water samples from 24 wells in the Water Quality Portal, run by the USGS and EPA, 2007 to 2023.
- PFAS: EPA tests of 11 town water systems in Hawaii County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Hawaii County is zone 3 on the EPA Map of Radon Zones.
- State programs and links: Department of Health, Safe Drinking Water Branch, checked November 1, 2026.