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

Rainwater harvesting is permissive in unincorporated Mariposa County. No county ordinance bans capturing rainwater, and at the state level the California Rainwater Capture Act of 2012 authorizes residential, commercial, and governmental landowners to install and operate rainwater-capture systems for rooftop runoff, with simple rain barrels and small landscape-irrigation systems generally exempt from a permit. This aligns with the County's General Plan Conservation and Open Space Element, Policy 11-2a, which directs water conservation consistent with state guidelines, and Implementation Measure 11-2a(1), which promotes drip irrigation and low-water landscaping. Practical limits in Mariposa County come from building and plumbing standards rather than a prohibition: larger storage tanks, elevated or structural supports, electrical pumps, and any system cross-connected to indoor or potable plumbing can require building permits and must satisfy California Plumbing Code and backflow-protection rules; potable reuse additionally involves Environmental Health review given the county's reliance on private wells and small water systems. Because the county is heavily forested and within a wildfire State Responsibility Area, large tanks can also serve as emergency water supply, which is encouraged. Owners planning anything beyond simple landscape-irrigation barrels should confirm requirements with the Mariposa County Building and Planning Departments before installation.