Summary of California’s Water Reuse Guideline or Regulation for Rainwater Collected Onsite for Potable Water Reuse

This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Rainwater Collected Onsite.

• Technical basis
• Types of planned potable reuse approved for use in California
• Water reuse treatment category/type
• Additional context and definitions
• Potable reuse specifications (table)
• Upcoming state law or policy
• References
• Disclaimer

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This page is a summary of the state’s water reuse law or policy and is provided for informational purposes only. Please always refer to the state for the most accurate and updated information. 

California allows potable water reuse potable water reuseThe use of highly treated recycled water for drinking water purposes. Includes the introduction of recycled water into an environmental buffer, such as groundwater aquifer or surface reservoir being withdrawn for potable purposes (indirect potable reuse), and the introduction of recycled water into a drinking water treatment facility or directly into a potable water distribution system (direct potable reuse). but does not provide specific potable use applications. The source of water (rainwater collected onsite) rainwater collected onsite Precipitation collected at the district or regional scale is classified separately under 'stormwater.' is specified by the state as rainwater. The write-up on this page uses state terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer's (REUSExplorer's) terms.

Technical basis

California allows the use of potable rainwater catchment systems for potable drinking water applications (Cal. Code Regs. tit. 24, § 5). Generally, potable water in the United States must meet all applicable Safe Drinking Water Act (SDWA) requirements, including its implementing regulations (40 C.F.R. § 141) for chemical and microbial contaminants and pollutant discharges from a point source for surface water augmentation require a federal National Pollutant Discharge Elimination Systems (NPDES) permit (40 C.F.R. part 122). The SDWA’s National Primary Drinking Water Regulations only apply to “public water systems,” which are systems for the provision to the public of water for human consumption through pipes or other constructed conveyances, if such systems have at least 15 service connections or regularly serve an average of at least 25 individuals daily at least 60 days out of the year. See SDWA section 1401(4) and 40 CFR 141.2. A permit is required for potable rainwater catchment systems in California and the system cannot have a direct connection to a public or private potable water supply or alternate water source system (Cal. Code Regs. tit. 24, § 5). Upon initial system startup, the quality of water for the intended potable application will be determined by the “Authority Having Jurisdiction,” which is defined as the federal, state, local, or other regional department or an individual such as a plumbing official, mechanical official, building official, or others having statutory authority (Cal. Code Regs. tit. 24, § 5). In the absence of water quality requirements, the minimal water quality must meet the requirements in the table below. The technical basis for developing the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators is not explicitly specified.

Types of planned potable reuse approved for use in California

Cal. Code Regs. tit. 24, § 5 does not provide specific potable use applications. 

Water reuse treatment category/type

California does not assign captured rainwater used for potable water use to a category or class of recycled water. 

Additional context and definitions

California defines potable rainwater catchment systems as “systems that use the principal of collecting and using rain from a rooftop or other man-made aboveground collection surface” for potable use (Cal. Code Regs. tit. 24, § 5). 

Potable rainwater catchment systems and components must be inspected and maintained according to Table K 101.5.1 in the California Plumbing Code unless more frequent inspection and maintenance are required by the manufacturer (Cal. Code Regs. tit. 24, § 5). A maintenance log must be maintained by the owner and available for inspection. Potable water filters must comply with NSF 53 (NSF/ANSI Standard 53) and be installed according to the manufacturer’s instructions. Potable water from a public or private potable water system is permitted to be used as makeup water to the rainwater storage tank provided the public or private potable water supply connection is protected by an air gap or backflow preventer (Cal. Code Regs. tit. 24, § 5).

A potable rainwater catchment system is not allowed to collect rainwater from vehicular parking surfaces, surface water runoff, or bodies of standing water (Cal. Code Regs. tit. 24, § 5). The collection surface for potable applications must be constructed of a hard, impervious material and approved prior to use. Roof coatings, paints and liners must comply with NSF Protocol P151. Tree branches and vegetation growth must be removed from over the roof or other rainwater collection surface. Rainwater tank openings must be protected to prevent entrance of insects, birds and rodents into the tank. Openings exceeding 12 inches in diameter must be secured to prevent tampering and unintended entry by humans (Cal. Code Regs. tit. 24, § 5).  

Potable reuse specifications

Summary of California's Potable Reuse Specifications

Sources = Cal. Code Regs. tit. 24, § 5 

* Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the state-specific regulations.

^a The Authority Having Jurisdiction is defined as “the organization, office, or individual responsible for enforcing the requirement of a code or standard, or for approving equipment, materials, installation, or procedures. The Authority Having Jurisdiction shall be a federal, state, local, or other regional department or an individual such as a plumbing official, mechanical official, building official, or others having statutory authority. In the absence of statutory authority, the Authority Having Jurisdiction may be some other responsible party.” (Cal. Code Regs. tit. 24, § 5). 

Upcoming state law or policy

No upcoming reuse regulations related to potable use of rainwater were found for California.

References:

2019 California Plumbing Code, Cal. Code Regs. tit. 24, § 5.

EPA-Administered Permit Programs: The National Pollutant Discharge Elimination System, 40 C.F.R. part 122.

Filtration Systems Standards, NSF/ANSI 42, 53 and 401.

National Primary Drinking Water Regulations, 40 C.F.R. § 141.

NSF International. NSF P151: Certification of Rainwater Catchment System Components.

Onsite Treated Nonpotable Water Systems, Cal. S.B. 966, Chapter 890, Cal. Stat. (2018).

Potable Reuse, Cal. Assemb. B. Chapter 528, Cal. Stat. (2017).
 

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Disclaimers

Please contact us at [email protected] if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.