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 2021 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.

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 2017 Water Efficiency and Sanitation Standard (WE•Stand). Also new in the 2021 edition is Appendix L: Tiny Houses, which was added to address safe and reliable plumbing system requirements for both permanent single tiny houses (Part I) and for tiny house communities (Part II).

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. 

NSPC Public Hearing Held August 11

The National Standard Plumbing Code (NSPC) Committee held the 2022 NSPC Public Hearing on August 11, 2022, at the Tropicana in Atlantic City, New Jersey. The NSPC proposed changes approved at the August hearing will appear in the 2024 National Standard Plumbing Code–Illustrated. The matrix of accepted changes can be accessed at the link below.

2024 NSPC Accepted Change Matrix 

Click here to download the 2024 NSPC Proposed Changes Monograph


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 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 


   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

   Email us at

NSPC Interpretation Inquiries

   Informal & Formal: Dan Cole, NSPC Secretary,