National Standard Plumbing Code

The National Standard Plumbing Code™ (NSPC)

First published in 1933, the NSPC is designed to ensure the proper installation of plumbing systems, providing local and state governments, code administration bodies, and the industry with a modern code to protect health and promote safety. In 2017, IAPMO and the Plumbing-Heating-Cooling Contractors—National Association (PHCC) executed an agreement transferring ownership of the NSPC to IAPMO. The transfer encompasses all editions of the NSPC and ensures the code can progress for years to come.

The 2024 National Standard Plumbing Code–Illustrated provides the latest information about common materials, fixtures, devices and equipment systems used or installed in plumbing systems. The NSPC contains revisions that have been included to promote sustainable plumbing practices. This new edition is printed in the popular illustrated format, with comments and illustrations clearly shown as supplemental information. The illustrations and supplementary notes make it an indispensable training tool.

Significant changes to the 2024 NSPC include the following:

  • New provisions for all gender toilet facilities
  • New provisions for adult changing stations
  • New standards for water closet compartments and urinal partitions
  • Wet Venting completely revised
  • Air admittance valves moved to Chapter 12
  • Appendix G, intended to promote safe and efficient water use in both residential and non-residential buildings,
  • has been updated with revised excerpts from the 2020 Water Efficiency and Sanitation Standard (WE•Stand)
  • IAPMO’s Water Demand Calculator included as a sizing option in Appendix G
  • New Appendix M addressing Impact of Water Temperature on the Potential for Scalding and Legionella Growth
  • New Appendix N providing requirements for Non-Sewered Sanitation Systems
  • New Appendix O addressing plumbing requirements for Indoor Horticultural Facilities.

Code Development

To keep the code current and viable and with input from all interested parties, the NSPC Committee — comprised of licensed contractors, engineers, inspectors and manufacturers — reviews the code annually and updates it on a three-year cycle. 

2027 NSPC Change Form

Deadline to Submit Proposed Changes
for 2027 National Standard Plumbing Code (NSPC) is Feb. 28

In order to facilitate the development of an updated National Standard Plumbing Code — Illustrated (NSPC), the IAPMO NSPC Committee requests proposed changes to the 2024 NSPC. All proposals are due by Feb. 28, 2025. Proposals accepted by the technical committee will appear in the 2027 NSPC.



Purchase 2024 National Standard Plumbing Code
Purchase 2021 National Standard Plumbing Code
Purchase 2018 National Standard Plumbing Code

   If you are ordering from New Jersey, please contact your state bookstore to order: 
   New Jersey: Phone (800) 652-7422 or email

Online Editions

   Read 2024 National Standard Plumbing Code
   Read 2021 National Standard Plumbing Code
   Read 2018 National Standard Plumbing Code
   Read 2015 National Standard Plumbing Code 

   Read 2021 NSPC-New Jersey Edition
   Read 2018 NSPC-New Jersey Edition 

Online IAPMO and ASSE Standards

   Read IAPMO ANSI Standards
   Read IAPMO Industry Standards
   Read ASSE ANSI Standards


   Download Errata to 2021 1st Printing
   Download Errata to 2018 2nd Printing
   Download Errata to 2018 1st Printing
   Download Errata to 2015 1st Printing  

   Download Errata to 2021 NSPC-New Jersey 1st Printing
   Download Errata to 2018 NSPC-New Jersey 1st Printing

NSPC Technical Committee

   NSPC Policies and Procedures
   NSPC Committee Application 

Have a Question

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NSPC Interpretation Inquiries

   Informal & Formal: Dan Cole, NSPC Secretary,