Rainwater laws / Hawaii
Is it legal to collect rainwater in Hawaii?
Checked at Hawaii's own statutes and agencies, November 2026. Not legal advice.
Allowed, and protected by law
Yes. Since Act 209 of 2026, every county must allow rainwater catchment for drinking and non-drinking uses on all properties.
What the rules say
- Act 209: "each county shall permit the installation and operation of rainwater catchment systems for potable and nonpotable uses on all properties."
- Counties "may require registration, inspection, or notification ... but shall not unreasonably restrict or prohibit their use."
- The state health department publishes water quality guidance for household catchment but doesn't regulate individual systems.
Before you buy a big tank
State law is only one layer. Cities and counties can set their own rules, especially for tanks plumbed into the house, and an HOA can limit where a barrel sits. Drinking rainwater needs treatment everywhere. For a barrel or two on a downspout for the garden, the state rule above is usually the one that matters.
Where the numbers come from
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