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

Capturing rain off your roof in unincorporated Mendocino County is broadly allowed and is governed by state law rather than a County ordinance. Under the Rainwater Capture Act of 2012 (AB 1750), a landowner is not required to obtain any permit or authorization from a local public agency to install, maintain or operate a rain barrel system, and residential, commercial and governmental landowners may operate rain barrel and rooftop rainwater-capture systems for outdoor, non-potable purposes. The State Water Board confirms that collecting and storing rainwater from rooftops does not require a water-right permit when the water is used for outdoor, non-potable uses. As a general guideline, simple rain-barrel/cistern storage captured from rooftops does not trigger building or plumbing permits when used for outdoor non-potable purposes; the commonly cited screening threshold is storage under about 360 gallons. Larger or more complex systems, those plumbed into a building for indoor use, or pressurized/potable systems, are subject to the California Plumbing Code and may require permits. Because all unincorporated land is a State Responsibility Area, residents should still site tanks and equipment so they do not conflict with defensible-space clearance near structures.