Monterey County, CA Landscaping Rules: Rainwater Harvesting (2026)
Key Facts
- Applies to
- ADU/JADU builds in North County LUP Area
- Zone
- Monterey County Coastal Zone (Title 20)
- Standard cited
- Chapter 18.05 (Plumbing Code)
- Alternative option
- Greywater system installation
- Mandatory fixtures
- 1.28-gal toilets, 1.8-gpm showerheads
Summary
For new accessory dwelling units proposed in the North County Land Use Plan Area of Monterey County's Coastal Zone, the county lets builders satisfy part of the mandatory groundwater-protection water conservation package by installing a rainwater catchment system built to Chapter 18.05 plumbing code standards, as an alternative to a greywater system.
For the Protection of Groundwater Resources in the North County Land Use Plan Area, when an ADU or JADU is proposed, water efficiency and conservation standards must be implemented... Additional water conservation measures may include one or more of the following, as applicable:i.Installation of a rainwater catchment system in compliance with Chapter 18.05 of this Code; orii.Installation of a greywater system in compliance with Chapter 18.05 of this Code.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 56).
Full Breakdown
Monterey County Code §20.64.030(D)(4), part of the Coastal Zoning Ordinance's Accessory Dwelling Unit and Junior Accessory Dwelling Unit regulations, imposes mandatory water efficiency and conservation standards on any ADU or JADU proposed in the North County Land Use Plan Area, adopted specifically 'for the Protection of Groundwater Resources,' before the Chief of Building Services may issue a building permit. Every structure on the lot must first meet fixed-fixture standards: toilets capped at 1.28 gallons per flush, showerheads at 1.8 gallons per minute, bathroom faucets at 1.2 gallons per minute, kitchen faucets at 1.8 gallons per minute, and Energy Star-certified clothes washers and dishwashers.
On top of those mandatory fixtures, §20.64.030(D)(4)(c) lists 'additional water conservation measures' the applicant may use 'as applicable,' offering two options: installing a rainwater catchment system, or installing a greywater system, each built 'in compliance with Chapter 18.05 of this Code,' the county's Plumbing Code chapter that adopts the California Plumbing Code with local amendments. The rainwater catchment option is not itself mandatory countywide; it is one compliance pathway inside a narrower, geographically limited mandate that applies only to ADU and JADU construction in the North County Land Use Plan Area within the Coastal Zone, not a general county-wide rainwater harvesting ordinance.
Violations & Fines
Building an ADU or JADU in the North County Land Use Plan Area without documenting compliance with §20.64.030(D)(4)'s water efficiency package, whether through the mandatory low-flow fixtures or one of the rainwater-catchment or greywater options, means the Chief of Building Services cannot issue the building permit; the application is returned rather than approved until the required documentation is submitted.
Frequently Asked Questions
Is rainwater harvesting required for all new construction in Monterey County?
What standard must a qualifying rainwater catchment system meet?
What is the alternative to installing a rainwater catchment system?
Sources & Official References
Other rules in Monterey County
California rules heatmap·Compare Monterey County to another location·View the California landscaping rules overview
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