The city does not provide cisterns for harvesting water. You may check with your water company. Some info about rain barrels and rebate info https://socalwatersmart.com/en/residential/rebates/available-rebates/rain-barrels-cisterns/
California. Rainwater harvesting coming from your roof is fine in California. No permit from the state board is necessary. However, collecting rainwater for landscaping purposes would require a license.
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