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

Rainwater harvesting is permitted and encouraged in Colusa County, and there is no county ordinance prohibiting or specially permitting rain barrels or cisterns on private property. The controlling authority is state law. The California Rainwater Capture Act of 2012 (AB 1750, codified at Water Code Division 6, Part 2.4) allows residential, commercial, and governmental landowners to install, maintain, and operate rain barrel and rainwater-capture systems and provides that a landowner is not required to obtain a permit from a local public agency to do so. The only exception is that, if installing a system requires disconnecting a downspout from the sewer system, the local agency may require a permit for proper disconnection and capping. The State Water Resources Control Board confirms that using rainwater collected from rooftops does not require a water-right permit. For larger or plumbed systems, the California Plumbing Code applies, and any system tied to potable plumbing or onsite reuse must meet state and local building/health standards. Colusa County's zoning landscaping guidelines (Section 44-3.10) promote efficient water use and on-site water retention consistent with these state policies. Within the cities of Colusa and Williams, those municipalities' codes apply.