Polybutylene Pipes: The Gray Plumbing Insurers Hate

Polybutylene (PB) was the cheap, flexible plumbing of the future from roughly 1978 to 1995. Then it started failing. Chlorine in municipal water degrades the pipe from the inside, so it can look perfect right up until it splits. It led to one of the largest class-action settlements in US building history, and many insurers still won't write a policy on it.

How to spot it

• Gray, sometimes blue or black, flexible plastic pipe, often stamped "PB2110"
• Visible near the water heater, under sinks, or where the main line enters the house
• Fittings that are plastic or copper crimp rings (the fittings were a major failure point)
• Build year in that 1978–1995 window, especially in the Sun Belt, where it was common

Don't confuse it with PEX, the modern flexible pipe. PEX is usually white, red, or blue and stamped "PEX".

Why insurance is the real problem

Some carriers decline homes with known polybutylene outright. Others surcharge, exclude water damage, or require proof of a repipe. Get an insurance quote before your inspection contingency expires, not at closing. A home you can't insure is a home you can't finance.

What a repipe costs

A whole-house repipe usually runs from several thousand dollars for a small single-story house to well over ten thousand for larger, multi-story homes. Drywall patching is extra. It typically takes a few days. Sellers who already repiped should have invoices. Ask.

Listing tells

"Updated plumbing" without specifics, "home warranty included," or a 1980s build with no mention of plumbing at all. In those cases, ask the listing agent directly what the supply lines are made of. The answer, or the dodge, is useful either way.