Well water hardness in Hawaii
Across 4 counties of Hawaii, the median well sampled by the USGS has 3.8 gpg of hardness. Counties range from 3.1 gpg (Hawaii County) to 9.9 gpg (Maui County).
Millions of American households drink water from their own well. No utility tests that water and no water quality report covers it. These pages summarise the hardness the U.S. Geological Survey measured in wells county by county, so you know what to expect before you test your own well.
Counties, hardest first
| gpg | mg/L | wells | ||
|---|---|---|---|---|
| Maui County | 9.9 | 170 | 18 | hard |
| Honolulu County | 3.9 | 66 | 68 | moderately hard |
| Kauai County | 3.7 | 63 | 11 | moderately hard |
| Hawaii County | 3.1 | 54 | 32 | soft |
Counties with fewer than 10 sampled wells, or a median outside 5–500 mg/L, are not shown until the figure is reviewed.