Also known as the PEX PLUMBING GUIDE
The third edition of the PEX Plumbing Distribution Systems Design and Installation Guide published in March 2026. This Guide is a joint industry publication from The Plastics Pipe Institute (PPI), The Plastic Pipe and Fittings Association (PPFA), Home Innovation Research Labs (HIRL), with support from IAPMO and ICC. It provides information and resources necessary to design and install crosslinked polyethylene (PEX) hot- and cold-water plumbing distribution systems in residential, multi-family, and commercial buildings.
This Guide first published in 2006 when PEX was making inroads into residential construction in North America. The second edition published in 2013 and included new information regarding the design and performance of PEX plumbing systems, based on laboratory work performed by HIRL for PPI. This third edition includes updates to reflect the advancements in PEX materials (e.g., tubing, manifolds, and fittings), updates to code acceptance for PEX plumbing systems, new design recommendations, and revisions to installation techniques. New information has been added to every chapter of this Guide, which also includes a new chapter about water service line applications with specific installation instructions.
Crosslinking technology for polyethylene was pioneered in Europe in the late 1960s, with the first PEX radiant heating systems installed in 1972. Since then, PEX has had a fifty-year history of successful use around the world for a variety of demanding applications. ASTM F876 Standard Specification for Crosslinked Polyethylene Tubing was first published in 1984, and PEX was first adopted into the BOCA National Plumbing Code in 1993 (BOCA became part of ICC) followed by rapid adoption into the other model plumbing codes across Canada and the US.
In addition to being the most common hot- and cold-water distribution material in residential plumbing, PEX tubing is now widely being used in commercial plumbing applications, due to its flexibility, resilience, proven performance, and potential time savings during installation. With so much new information to share, as well as the knowledge learned from over thirty years of North American plumbing applications, PPI members felt it was time to do a total re-write of this guide, while also including many more pictures and graphics to make it easier to follow. Therefore, the third edition is completely new and is targeted to meet the needs of plumbers, home builders, designers, and engineers.
PPI is grateful to our members who provided pictures, graphics, technical content, and many hours of collaboration to finalize the third edition. We also recognize significant contributions from PPFA, IAPMO, and ICC in making this Guide a reality. It was prepared by the Home Innovation Research Labs (HIRL).