California Green Building Code (CALGreen) – Nonpotable water systems

To encourage the use of nonpotable water systems in order to preserve potable water and to provide a reference for the requirements of the California Plumbing Code.

CALGreen Code Section A5.305.1: Nonpotable water systems.

Nonpotable water systems for indoor and outdoor use shall comply with the current edition of the California Plumbing Code.


The intent of this measure is to promote the use of nonpotable water systems to conserve potable water, and to reference the California Plumbing Code for requirements. The 2019 California Plumbing Code includes provisions for the installation of nonpotable systems. There may be local prohibitions or requirements for the use of nonpotable water systems.

Compliance Method:

Provide a nonpotable water system complying with the California Plumbing Code, as acceptable to the local jurisdiction. Detail in construction documents the nonpotable water system piping plan and specifications for system components.


Plan intake: The plan reviewer should confirm in the construction documents the nonpotable system piping plan and component specifications. The reviewer should make sure that the nonpotable system for irrigation meets applicable local, regional and state standards.

On-site enforcement: The inspector should verify that the system is installed as shown in the drawings, using specified components.

(Excerpted from ‘Guide to the 2022 California Green Building Standards Code Nonresidential’ – Appendix A5)

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