On August 1, 2023, the California Building Standards Commission approved the adoption of Uniform Plumbing Code (UPC) Appendix M into the California Plumbing Code (CPC). UPC Appendix M is an alternative methodology to the CPC Appendix A for sizing water pipes in new single family and multifamily buildings. This alternative approach will be available for statewide use on a voluntary basis effective July 1, 2024. Learn more by reading our fact sheet.
This adoption is a culmination of advocacy that started in 2021. The Statewide Utility Codes and Standards Team submitted a Title 24 Petition to adopt UPC Appendix M into the CPC during the 2022 Intervening Code Adoption Cycle. The petition was supported by CalWEP and 15 CalWEP member agencies.
Using UPC Appendix M for sizing water pipes in residential occupancies provides upfront and ongoing cost savings, water savings, embedded energy savings, and natural gas savings. The benefits of not oversizing water pipes also include reduced risk to public health and safety and reduced carbon emissions due to material savings and energy reductions.