This code is founded upon certain basic principles of environmental sanitation and safety through properly designed, acceptably installed, and adequately maintained plumbing systems. Some of the details of plumbing construction may vary, but the basic sanitary and safety principles desirable and necessary to protect the health of the people are the same everywhere. As interpretations may be required, and as unforeseen situations arise that are not specifically covered in this code, the 23 principles in items A to W shall be used to define the intent.

2021 National Standard Plumbing Code Illustrated provides the latest information about common materials, fixtures, devices and equipment systems used or installed in plumbing systems. It is compatible with codes used nationwide and follows the numerical sequence of ANSI A.40.8. The code contains many revisions that have been included to promote sustainable plumbing practice. Appendix G is intended to promote sustainable plumbing practice and has been updated with revised excerpts from the IAPMO Green Plumbing and Mechanical Code Supplement. Used in conjunction with PHCC's Plumbing Apprentice Training Program, the guide's illustrations and supplementary notes make it an indispensable training tool.

The 2003 International Plumbing Code addresses the design and installation of plumbing systems through requirements that emphasize performance. Provisions are provided for fixtures, piping, fittings, and devices as well as design and installation methods for water supply, sanitary drainage, and storm drainage. The code provides comprehensive minimum regulations for plumbing facilities using prescriptive- and performance-related provisions. The objectives of the code provide for the acceptance of new and innovative products, materials, and systems. The 2003 edition is fully compatible with all the International Codes published by the International Code Council (ICC).