How to identify it
Look at the water heater, under sinks and at the meter for flexible gray pipe stamped PB2110. Fittings may be gray plastic or copper/aluminum crimp rings.
Why it fails
Disinfectants in public water are widely cited as degrading PB and its fittings over time. Failures can be sudden, often at fittings, and often in the attic or walls.
Insurance and resale
Some insurers decline or surcharge homes with PB, and buyers increasingly ask for repipes during negotiation.
Now or later?
If you have PB, the question is usually when, not if. A planned repipe costs less than an emergency repipe plus water damage. Get an independent repipe evaluation, and check your home's overall risk with the Plumbing Health Score.