Polybutylene pipe
Also called: poly-B, PB pipe, PB2110, gray plastic pipe, Quest pipe
Gray (sometimes blue or black) plastic supply pipe installed in millions of US homes from 1978 to 1995, stamped PB2110. It degrades from chlorine in water and fails at the fittings without warning. Insurers often decline or surcharge homes that still have it; the fix is a full repipe.
Polybutylene was the cheap, flexible supply pipe of its era — the PEX of the 1980s — until it turned out that chlorine and other oxidants in municipal water make it brittle from the inside. The pipe flakes, the acetal (plastic) fittings crack, and the failures are sudden: no drip, then a wall full of water. A class-action settlement (Cox v. Shell, 1995) paid for replacements for years, and installation stopped in the mid-1990s.
How to tell: gray, 1/2 or 3/4 in flexible pipe, often with copper crimp rings at the fittings, stamped “PB2110” along its length. Look at the water heater connections, under sinks, and where the main enters the house. It was used for the main service line too, often in blue.
There’s no repair. A house with polybutylene supply lines gets a full repipe in PEX or copper, and the permitted, inspected job is the document that satisfies the insurer and the next buyer’s inspector. Until then, expect some insurers to decline coverage or add a surcharge, and disclose it at sale. Galvanized steel supply pipe (pre-1970s, rusts shut and sheds rust) is the other material in the same replace-not-repair category.