Polybutylene is a gray plastic water supply line pipe that was developed in the 1970’s and promoted as “the pipe of the future.” At the time, the perceived advantages of poly were the low cost over copper and the ease of installation. But in the 1980’s structures with poly started reporting leaks. When the poly pipes were replaced, it was noticed that the interior walls of the pipes and fittings were breaking down and flaking apart.

From 1978 to 1995, millions of homes, mobile homes apartment buildings and commercial structures were built with poly or had poly installed during remodeling. The fitting pictured on the right was still holding up despite the internal decay and flaking. It looked fine on the outside, but fortunately the homeowner decided to replace the poly system before the problems started.

The Problem with "Poly", "Poly-B" or "PB"

Poly systems may fail without warning, damaging properties and personal belongings, and disrupting lives. Factors that may contribute to poly’s failure include: chemicals in our water supply, such as chlorine, that slowly destroy the structural integrity of poly pipes and fittings; the age of the pipe ‐ the older the pipe, the more likely a problem will occur; and faulty installation.

Check Your Pipes

Inside Your Home: Any gray plastic pipe could be poly. Look at pipes near the water heater and see what kind of pipe runs across the ceiling in an unfinished basement. Check the pipe that comes out of walls to feed sinks and toilets. Many properties have a combination of copper and poly pipes.

Underground Water Main: Underground poly pipes can be blue, black or gray. They are found entering properties through the basement wall or floor, concrete slab or coming up through a crawlspace. They most often enter properties near the water heater. Your main shutoff valve is attached to the end of the outside water main.

So You Have Poly Pipes - Now What?

Even if you know you have poly pipes, you still can’t tell what condition they’re in just by looking at or squeezing them because the problems occur on the inside of the pipes. Failures may occur in systems with plastic fittings, metal fittings, and manifold‐type systems that look fine even to the trained eye. You must prioritize your home maintenance requirements and budget accordingly. Unlike most other maintenance issues, delayed replacement of poly may have substantial consequences. Due to the many documented cases of leaks, plumbing experts recommend replacing poly pipes.

Replacement of Poly Pipes

Although replacement can be done at anytime, it’s easier and less expensive if you replace it while the house is vacant. You may even be able to roll the cost into your mortgage. Replacement entails abandoning all poly pipes and installing a new system. You should look for a company that specializes in poly replacement, not just plumbing in general. Not all homes have had leaks, but the problem is, it’s impossible to tell if a home will have problems, or when. Unlike most other home maintenance issues, delaying poly replacement may have devastating consequences. While pipe replacement is a “hidden” investment, it will increase the value of your home, unlike many other home improvements.