Rainwater laws / Oklahoma
Is it legal to collect rainwater in Oklahoma?
Checked at Oklahoma's own statutes and agencies, November 2026. Not legal advice.
Allowed; plumbing rules for indoor use
Yes. Rainwater systems follow the Oklahoma plumbing code, which requires an automatic first-flush diverter.
What the rules say
- EPA: rainwater systems "must abide by the minimum standards set by the Plumbing Code 2018 of Oklahoma," and an "automatic first-flush diverter" is required.
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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