Thousand Oaks, CA Landscaping Rules: Rainwater Harvesting (2026)
Key Facts
- Permit Required
- No for standard rain barrels
- Large Systems
- Permit for >5,000 gallons
- Legal Authority
- CA Water Code Section 10574
- Average Rainfall
- 18-20 inches annually
- Mosquito Prevention
- Screened/covered containers
Summary
Rainwater harvesting is legal and encouraged in Thousand Oaks under California Water Code Section 10574. Residential rain barrel installations do not require permits, and the city supports stormwater capture as part of its water conservation and watershed protection programs.
PART 2.4. Rainwater Capture Act of 2012. 10570. This part shall be known, and may be cited, as the Rainwater Capture Act of 2012. ... 10573. Solely for the purposes of this part, and unless the context otherwise requires, the following definitions govern the construction of this part: (a) "Developed or developing lands" means lands that have one or more of the characteristics described in subparagraphs (A) to (C), inclusive, of paragraph (4) of subdivision (b) of Section 56375.3 of the Government Code. (b) "Rain barrel system" is a type of rainwater capture system that does not use electricity or a water pump and is not connected to or reliant on a potable water system. (c) "Rainwater" means precipitation on any public or private parcel that has not entered an offsite storm drain system or channel, a flood control channel, or any other stream channel, and has not previously been put to beneficial use. (d) "Rainwater capture system" means a facility designed to capture, retain, and store rainwater flowing off a building rooftop for subsequent onsite use. ... 10574. Use of rainwater collected from rooftops does not require a water right permit pursuant to Section 1201.
Full Breakdown
Rainwater harvesting from rooftop surfaces is explicitly authorized under California Water Code Section 10574 for any beneficial use. Thousand Oaks residents may install rain barrels and small cisterns without permits for standard residential systems. Larger systems exceeding 5,000 gallons may require building permits for structural safety. The city's stormwater management program encourages on-site capture through rain barrels, rain gardens, and permeable surfaces. The Conejo Valley's average annual rainfall of approximately 18-20 inches, concentrated in winter months, makes storage systems valuable for extending water availability. Captured rainwater may be used for landscape irrigation, garden watering, and non-potable outdoor uses. The city occasionally partners with water agencies to offer rain barrel distribution events.
Violations & Fines
Rainwater harvesting does not generate violations. Systems creating standing water that breeds mosquitoes may be cited by the Ventura County Environmental Health Division. Unpermitted large cisterns may require retroactive permitting. Runoff directed onto neighboring properties constitutes a nuisance.
Frequently Asked Questions
Is rainwater harvesting legal in Thousand Oaks?
What size rain barrel do I need?
Are there rain barrel programs in Thousand Oaks?
Sources & Official References
Other rules in Thousand Oaks
California rules heatmap·Compare Thousand Oaks to another location·View the California landscaping rules overview
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Rainwater Harvesting in Nearby Cities
How other cities in Ventura County handle rainwater harvesting.