By using nonpotable water systems (such as collected rainfall, treated graywater, and recycled water) designed to feed toilets, urinals, and other permitted purposes, this code provision aims to limit the amount of potable water used inside.
CALGreen Code Section A5.303.2.3.4: Nonpotable water systems for indoor use.
Utilizing nonpotable water systems (such as captured rainwater, treated graywater and recycled water) intended to supply water closets, urinals, and other allowed uses, may be used in the calculations demonstrating the 12, 20 or 25 percent reduction. The nonpotable water systems shall comply with the current edition of the California Plumbing Code.
The intent of this code measure is to reduce indoor potable water use by utilizing nonpotable water systems (such as captured rainwater, treated graywater and recycled water) intended to supply water closets, urinals and other allowed uses. Section 5.303.2 of this code mandates reduced flow rates or gives an exception for a 12-percent reduction in indoor potable water use through a performance approach. If a tier is adopted by your city or county, a 20- or 25-percent reduction will likely be required, and there may be a local ordinance in place otherwise for a reduction in water usage. CBSC and HCD promulgated this code change to provide clarity in reference to provisions of the plumbing code, being proposed simultaneously for nonpotable water systems.
Comply with the California Plumbing Code requirements for the use of alternate nonpotable water systems.
Plan intake: The plan reviewer should review the construction documents to confirm that alternate nonpotable plumbing standards in the California Plumbing Code, Chapters 15 and 16 are used in the design.
On-site enforcement: The inspector should verify that the specified nonpotable water system for indoor use is installed.
(Excerpted from ‘Guide to the 2022 California Green Building Standards Code Nonresidential’ – Appendix A5)