Polybutylene plumbing (also known as PB plumbing) is a gray flexible potable water supply line used in many valley homes from the late 70’s to the mid 90’s. There have been numerous reports of failure and class action lawsuits with this plumbing system. Expert opinions regarding the failures include:
- Plastic fittings are stressed and crack by pressure used to secure the fittings.
- Brass fittings can increase the rate of oxidation, making the pipe brittle and prone to cracking over time.
- The metal fittings and plastic piping have different expansion rates, exerting pressure on the connections, causing the pipes to sprout leaks or rupture.
The subject has always been controversial and it’s easy to find plumbing experts on both sides of the argument. Some will say that PB is inherently flawed and should be replaced in all homes. Others insist that the problems with PB have nothing to do with bad pipes and are more a result of improper installation or poor building practices. Either way it has been estimated that 80,000 Arizonans have had problems with PB plumbing lines.
Homes with PB plumbing put home inspectors in a tough situation. Home inspections are a visual assessment and, almost always, everything looks just fine. However, it’s hard not to be concerned about potential future problems and water damage that may occur. It has been reported that complex polymers in the PB plumbing lines have a nasty habit of breaking down when exposed to chemicals, like chlorine, that are commonly used in water treatment systems. Pipes and fittings get brittle, micro-fractures develop, and failures can happen without warning. Worse, this deterioration is progressive (the longer pipes are exposed, the greater the chance of failure). In some cases, homeowners are finding that homeowners’ insurance companies will either cancel their coverage when extensive damage is caused by PB or refuse coverage to homes piped with PB. For these reasons I always recommend the buyer contact a licensed plumber for further information and recommendations.
Cost of replacing PB plumbing very depending on the size of the home and type of material used to replace the PB plumbing (copper, CPVC, PEX). A ballpark estimate would be between $4,000 and $7,000. You will need to get two estimates: one from a plumber and one from a general contractor to repair the walls and ceiling after the plumbing has been replaced.