- Q.I would like to use black
polyethylene water service pipe for plumbing in the
crawlspace of a house that has a black poly service
line. Are there any code limitations on using
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).