Hawaii Well Water
Last reviewed October 29, 2026
Overview
Private wells supply water to many Hawaii households. Because they are generally not regulated like public systems under the federal Safe Drinking Water Act, testing and wellhead protection are the owner’s responsibility.
Hydrogeology & what it means
Hawaii’s drinking water comes largely from volcanic basal and dike-confined aquifers, generally of good quality. The documented regional concerns below indicate what is worth testing for — not what any individual well contains.
Documented regional concerns
- Saltwater intrusion and elevated chloride/sodium in coastal or over-pumped areas.
- Naturally acidic (low pH) water that can corrode plumbing and leach metals such as lead or copper.
These are documented possibilities, not a reading of your well
Frequently asked questions
What should well owners in Hawaii test for?
A practical panel for Hawaii private wells includes Total coliform bacteria, Nitrate (as N), pH, Chloride, Total dissolved solids, Lead, Copper. Test bacteria and nitrate at least annually and use a state-certified laboratory; confirm local recommendations with your state health department and University of Hawaiʻi Cooperative Extension.
Are private wells regulated in Hawaii?
Private wells are generally not covered by the federal Safe Drinking Water Act, though Hawaii or local rules may apply to construction, permitting, or testing. Public-system limits such as EPA MCLs are useful reference points, not automatic legal limits for your well.