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

Rainwater harvesting is allowed in unincorporated Monterey County 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 exempt from the State Water Resources Control Board's water-rights permit requirement. For typical home use, collecting rooftop rainwater in a barrel or small cistern for outdoor, non-potable purposes generally does not require building or plumbing permits. Larger cisterns, potable or indoor uses, and pressurized/pumped systems can trigger California Plumbing Code review and a permit, so owners installing bigger or plumbed systems should confirm with Monterey County Building Services before construction. Because water supply is constrained across much of the county (especially the Monterey Peninsula under MPWMD), capturing rainwater is encouraged as a way to reduce potable demand and complements the County's water-conservation goals. Graywater systems are a related, separate matter governed by the California Plumbing Code, where simple single-fixture (e.g., clothes-washer) graywater systems can be installed without a permit, while more complex graywater systems require a permit and must meet plumbing-code standards. Always verify whether your water district or any HOA imposes additional requirements; California Civil Code 4735 limits HOAs from banning water-efficient landscaping.