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

Merced County does not appear to have a distinct rainwater-harvesting ordinance, so the controlling rules are statewide. Under California's Rainwater Capture Act of 2012 (AB 1750, codified at Water Code Part 2.4, Section 10574), residential, commercial and governmental landowners may install and operate rain barrels and rainwater capture systems. Collecting rooftop rainwater does not require a water-right permit from the State (it is exempt from the permitting otherwise required under Water Code Section 1201). For simple systems, harvested rainwater is intended for outdoor, non-potable uses such as landscape irrigation, and basic rain barrels/cisterns (commonly under 360 gallons, used per manufacturer instructions) are typically installed without a building permit. Practically, this complements the County's water-efficiency goals in UDO Chapter 18.36 - capturing rain reduces reliance on potable irrigation. However, larger or more complex systems do face oversight: cisterns above local size/weight thresholds, plumbing tie-ins, pumps, or any indoor/potable reuse can require a building or plumbing permit and must meet California Plumbing Code and health standards, and overflow must drain safely to landscaping or a storm drain. Always confirm setback, overflow and permit specifics with Merced County Building & Safety before installing a large tank or connecting a system to household plumbing. There is no County prohibition on residential rain collection.