Orange County, CA Landscaping Rules: Rainwater Harvesting (2026)

Rainwater harvesting in unincorporated Orange County is allowed and is governed primarily by California state law rather than a special county ordinance. The Rainwater Capture Act of 2012 (AB 1750) authorizes residential, commercial, and governmental landowners to install and operate rain-barrel and rainwater-capture systems, and provides that the use of captured rainwater is not subject to the State Water Resources Control Board's water-rights permit requirement. For typical home use, collecting rooftop rainwater in a rain barrel or cistern used for outdoor, non-potable purposes generally does not require building or plumbing permits, especially for smaller containers. Larger or more complex systems, potable or indoor uses, pressurized/pumped systems, or systems exceeding common size thresholds can trigger plumbing-code review and permits, so owners with bigger cisterns should confirm with OC Public Works Building & Safety. Because rainwater capture reduces potable demand, it complements the County's water-efficiency goals. Always verify whether your specific water district or any HOA imposes additional design or screening requirements; California Civil Code 4735 limits HOAs from banning water-efficient landscaping outright.