Sonoma, CA Landscaping Rules: Rainwater Harvesting (2026)
Key Facts
- Non-spray irrigation exemption
- Up to 5,000 gallons
- Spray irrigation exemption
- Up to 360 gallons
- Tank ratio limit
- Height-to-diameter ≤ 2 to 1
- Disqualifying features
- Electrical power or makeup water line
- Code currency
- Ord. 13-2025, Dec. 3, 2025
Summary
The City of Sonoma exempts small rainwater catchment tanks from a plumbing permit: up to 5,000 gallons for non-spray irrigation and up to 360 gallons for spray irrigation, under Sonoma Municipal Code § 14.10.010. Larger tanks, or ones needing electrical power or a makeup water line, need a plumbing permit under the adopted California Plumbing Code.
3. Exterior rainwater catchment systems used for outdoor non-spray irrigation with a maximum storage capacity of 5,000 gallons where the tank is supported directly upon grade and the ratio of height to diameter or width does not exceed 2 to 1 and does not require electrical power or a makeup water supply connection. ... 4. Exterior rainwater catchment systems used for spray irrigation with a maximum storage capacity of 360 gallons.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 13-2025, passed December 3, 2025).
Full Breakdown
2 to list plumbing work exempt from a permit, and two of those items cover rainwater harvesting directly. Item 3 exempts exterior rainwater catchment systems used for outdoor non-spray irrigation with a maximum storage capacity of 5,000 gallons, so long as the tank sits directly on grade, the height-to-diameter ratio does not exceed 2 to 1, and the system needs no electrical power or makeup water supply connection. Item 4 separately exempts exterior rainwater catchment systems used for spray irrigation, but caps those at a much smaller 360-gallon capacity, reflecting the added risk spray irrigation systems carry.
030. As with every item on the exemption list, going without a permit for an exempt system never authorizes work done in violation of any other code section or city ordinance. These provisions are current through Ordinance 13-2025, adopted by the city council on December 3, 2025, so residents planning a larger cistern system should confirm current requirements with the Sonoma building department before installation.
Violations & Fines
Installing an oversized or electrically connected rainwater catchment system without the required plumbing permit is a Chapter 14.10 SMC violation, punishable under § 1.12.010(A)(4) by a fine up to $100 for a first offense, $500 for a second offense of the same section within a year, and $1,000 for a third, plus an investigation fee under § 109.4.
Frequently Asked Questions
Do I need a permit for a rain barrel or cistern in the City of Sonoma?
Is the rainwater tank size limit different for spray irrigation in Sonoma?
What code governs a permitted rainwater system in the City of Sonoma?
Sources & Official References
Other rules in Sonoma
California rules heatmap·Compare Sonoma to another location·View the California landscaping rules overview
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Rainwater Harvesting in Nearby Cities
How other cities in Sonoma County handle rainwater harvesting.