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Dual Plumbing Code

The California Plumbing Code contains design standards to safely plumb buildings with both potable and recycled water systems. These statewide standards apply for installing both potable and recycled water plumbing systems in commercial, retail, and office buildings, theaters, auditoriums, condominiums, schools, hotels, apartments, barracks, dormitories, jails, prisons, and reformatories. These standards are found in Chapter 16A, Part II of the 2013 California Plumbing Code (California Code of Regulations, Title 24, Part 5). To view Chapter 16A, Part II, click here. Chapter 16A is titled Non-Potable Water Reuse System, but informally this has been referred to as the Dual Plumbing Code.

Due to copyright restrictions, printed copies of any portion of the California Plumbing Code must be obtained through the bookstore of the International Association of Plumbing and Mechanical Officials.

Development of Dual Plumbing Code

The Dual Plumbing Code is adopted by the California Department of Water Resources (DWR) under authority of California Water Code, Division 7, Chapter 7, Article 7, section 13557. Section 13557 was established by the State Legislature in Assembly Bill No. 371 (2006) and amended in Senate Bill No. 283 (2009).

The procedure for adopting the dual plumbing code includes several steps: adoption by DWR in consultation with the California Department of Public Health, approval by the California Building Standards Commission, and publication in the California Plumbing Code. This initial dual plumbing code was adopted by DWR in 2009. On November 18, 2009 the California Building Standards Commission unanimously voted to approve the California dual plumbing code. The standards were published in the 2010 California Plumbing Code, Chapter 16A, Part II. They became effective January 2011. The dual plumbing code section was not revised when the California Building Standards Commission adopted the 2013 California Plumbing Code.

Background and Historical Documents on Dual Plumbing Code

2010 California Plumbing Code:

1. Information Flyer (July 2009)

2. Final Proposed Code Submitted CBSC 10/28/09

3. Previous Versions
(07/13/09 version)
(06/25/09 version)
(05/13/09 version)
(04/24/09 version)

4. Statement of Reasons
The Statement of Reasons provides the legal and technical basis for the regulations.
(Initial Statement of Reasons)7/13/2009
(Final Statement of Reasons)10/28/2009

5. Public Workshops - Sacramento (5/11/09) - San Diego (5/20/09)
Press Release
(Agenda)

Authorizing Legislation:

SB 283 (DeSaulnier, 2009) - Department of Water Resources: recycled water system

AB 371 (Goldberg) - The Water Recycling Act of 2006


California Recycled Water Task Force

The initial basis for the dual plumbing code regulations was an analysis by the Recycled Water Task Force of the California Plumbing Code in effect in 2002, which incorporated dual plumbing code provisions from the Uniform Plumbing Code that were never officially adopted for California use and which were unsuitable for California conditions.

The Plumbing Code/Cross-Connection Control Workgroup, a working group advising the 2002 Recycled Water Task Force, drafted design standards for dual plumbed buildings for potable and recycled water systems. This proposed draft was the starting point for the dual plumbing code provisions in the 2010 California Plumbing Code. The analysis and recommendations of the Recycled Water Task Force can be found in two documents:

Water Recycling 2030: Recommendations of California’s Recycled Water Task Force, June 2003

Plumbing Code / Cross Connection Control Workgroup Draft White Paper, 15 November 2002


More Information

For information regarding the California Plumbing Code, Chapter 16 - Part II please use the Water Recycling and Desalination Staff Contact information.