Downey, CA Landscaping Rules: Rainwater Harvesting (2026)

Water Code Section 10573 defines the terms that control this exemption. A "rain barrel system" is a rainwater capture system that uses no electricity or water pump and is not connected to or reliant on the potable water supply, covering the standard backyard barrel under a downspout. A broader "rainwater capture system" is any facility designed to capture, retain and store rainwater flowing off a building rooftop for later onsite use, which reaches larger cisterns and tanks as well as barrels. "Rainwater" itself is defined narrowly: precipitation on a public or private parcel that has not entered an offsite storm drain, flood control channel or other stream channel, and that has not already been put to beneficial use elsewhere.

3(b)(4)(A)-(C). Section 10574 supplies the operative rule: using rainwater collected from rooftops does not require a water right permit under Water Code Section 1201, the section that normally governs appropriations of state water. That means a Downey homeowner who sets up a rain barrel or cistern under a roof downspout and reuses the water on-site for landscaping does not have to apply to the State Water Resources Control Board's Division of Water Rights before doing so, so long as the setup fits the Section 10573 definitions.

Section 10574 was added by AB 1750 (Stats. 2012, Ch. 537, Sec. 2), effective January 1, 2013. Section 10573's definitions were later amended by SB 985 (Stats. 2014, Ch. 555, Sec. 6), effective January 1, 2015, to add the current stormwater and developed-lands cross-references.