Nice PEX

Plastic water supply pipe.

“Nice pecs” used to be a personal compliment. Of course this was a long time ago. Back in that day, copper was used for water supply plumbing. Plastic water pipe has been used in residential construction for about twenty years now. Plastic pipe is lower cost both to purchase and install. The most common plastic pipe is called PEX. This is cross-linked polyethylene. The X stands for cross linking and this happens at the molecular level, it doesn’t describe the spider web of plastic pipe that you may find in the basement around your water heater. The cross linking of polymers results in a material that is more resistant to deformation and flow, but is less flexible.

There were many growing pains along the way with the advent of plastic water pipe. There are almost too many lawsuits to keep track of for pipe or fitting failures. Complicated by geographical temperature extremes, local building practices, and local water conditions, these lawsuits that originated all over North America were not necessarily reflective of valid issues in the Canadian GTA house. The lawsuits mostly related to leakage at fittings, and less often to actual pipe failure. Mostly the brass fittings were problematic, with an issue called dezincification.

Many of the early issues have been resolved and for the past 8 years or so plastic pipe issues seemed to have calmed down. If you have “old” (about pre-2008) plastic pipe in the house it’s worth checking for any signs of leakage or oozing at fittings, especially close to the water heater.

by Keith Tripp, 2016