Q&A: Polyethylene Water Service Pipe

A.Master plumber Rex Cauldwell responds: Polyethylene pipe is not approved for in-house cold or hot water lines. According to the International Building Code, once the polyethylene service pipe enters the building, you must terminate it within 5 feet. Whether you consider the crawlspace part of the building is up to you and the inspector.

The intent of the code is to prevent the poly pipe from being used for the in-house water lines. If you use polyethylene pipe to go directly to a water pressure tank without any take-offs to fixtures — or, for city water, to go straight to a main valve in the crawlspace — you are probably following the intent of the code, even if you have more than 5 feet of polyethylene pipe in the crawlspace. What you definitely do not want to do is tee off from the polyethylene pipe. No tees should be installed until after the polyethylene hits the main valve and transitions to the in-house piping (for example, to copper or PEX).