Polybutylene and Galvanized Pipe

Galvanized steel

How to recognise it: grey metal pipe with threaded joints, often in older homes and some additions. A magnet sticks to it.

The problem: galvanized pipe corrodes from the inside. Rust builds up and narrows the pipe, reducing water pressure. Water may run brown after sitting. Eventually joints leak.

What to do: plan replacement. It is not an emergency unless leaking, but pressure and water quality improve noticeably once it is gone.

Polybutylene

How to recognise it: grey, at times blue or black, flexible plastic pipe, often marked PB with crimp rings or plastic fittings. Installed in some houses from roughly 1978 into the mid-90s.

The problem: polybutylene has a history of failing, particularly at fittings, sometimes without warning. Some insurers ask about it or adjust coverage.

What to do: replace when practical. If you are renovating, take the opportunity.

Replacing either

Replacement is usually done with copper or PEX. Most of the work is in the basement, where mains run along the joists, with branches up through walls to bathrooms and the kitchen. See repiping for how it is done.

Electrical grounding

Older homes sometimes use metal water pipe as part of the electrical ground. Replacing metal with plastic can break that path. An electrician should confirm a proper ground before old pipe is removed.

Buying a home with either pipe? See checks before buying.