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.
National Standard Plumbing Code™ Public Hearing Held Aug. 14
The NSPC Committee held the 2025 NSPC Public Hearing on August 14, 2025, at Caesars Resort & Casino in Atlantic City, New Jersey. The NSPC proposed changes approved at the August hearing will appear in the 2027 National Standard Plumbing Code–Illustrated.
Final 2027 Matrix of Changes
The 2027 Matrix of Changes with the final committee actions taken at the hearing is available here.
Amended Proposals
The proposed changes that were accepted as amended by the committee during the hearing can be downloaded here.
2027 NSPC Proposed Changes Monograph
The 2027 NSPC Proposed Changes Monograph is available at the link below.
NATIONAL STANDARD PLUMBING CODE
Order, View Online Editions, or Download Errata of the National Standard Plumbing Code
Ordering
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 director@nj-phcc.org
View Online IAPMO and ASSE Standards
Read IAPMO ANSI Standards
Read IAPMO Industry Standards
Read ASSE ANSI Standards
NSPC Technical Committee
Have a Question
Email us at nspc@iapmo.org
NSPC Interpretation Inquiries
Informal & Formal: Dan Cole, NSPC Secretary, dan.cole@iapmo.org