A grey (sometimes blue or black) flexible plastic supply pipe installed in Canadian homes most commonly from 1978 to about 1997 — by some estimates in more than 700,000 Canadian homes — as a cheap, fast alternative to copper. It was eventually discontinued and removed from Canada's plumbing code (around 2005) as its reliability problems became clear.
$4,000–15,000 to repipe a houseAddress before purchasePlumbing
Why it matters
Poly-B can fail without obvious warning. It degrades over time — chlorine and other oxidants in municipal water attack it from the inside, and stress concentrates at the fittings — and it can split or leak, sometimes causing sudden, expensive water damage. The two practical headaches for a buyer are that water damage andinsurance: a growing number of Canadian insurers won't cover an active poly-B home, or will add water-damage surcharges, exclusions, or higher deductibles. That combination makes it a before-you-buy conversation, and a strong negotiation point.
How to spot it
Grey flexible plastic supply lines — not white/translucent PEX and not copper — at the water heater, under sinks, and at the main shutoff, joined with plastic or copper crimp fittings. If you can read the pipe it's often stamped "PB2110."
What it costs
Roughly $4,000–15,000 to repipe a house, depending on size, access, and finishes.
What to do
Address before purchase. Have a licensed plumber confirm the material and extent and quote a repipe, and — importantly — confirm coverage with your insurer or broker before removing conditions. Use the quote to negotiate.
Education and triage, not a home inspection. Casaroo flags grey poly-B from your photos — a licensed plumber confirms the type and extent.
Common questions
What is Polybutylene (poly-B) plumbing?
A grey (sometimes blue or black) flexible plastic supply pipe installed in Canadian homes most commonly from 1978 to about 1997 — by some estimates in more than 700,000 Canadian homes — as a cheap, fast alternative to copper. It was eventually discontinued and removed from Canada's plumbing code (around 2005) as its reliability problems became clear.
Why does it matter for home buyers?
Poly-B can fail without obvious warning. It degrades over time — chlorine and other oxidants in municipal water attack it from the inside, and stress concentrates at the fittings — and it can split or leak, sometimes causing sudden, expensive water damage. The two practical headaches for a buyer are that water damage andinsurance: a growing number of Canadian insurers won't cover an active poly-B home, or will add water-damage surcharges, exclusions, or higher deductibles. That combination makes it a before-you-buy conversation, and a strong negotiation point.
How can I spot it?
Grey flexible plastic supply lines — not white/translucent PEX and not copper — at the water heater, under sinks, and at the main shutoff, joined with plastic or copper crimp fittings. If you can read the pipe it's often stamped "PB2110."
How much does it cost to fix?
Roughly $4,000–15,000 to repipe a house, depending on size, access, and finishes.
Note: poly-B is a discontinued product, so guidance comes from industry and insurers rather than a single government standard; insurer positions vary — confirm with your broker, and a licensed plumber confirms the pipe. Casaroo flags, it does not inspect.
Last reviewed 2026-06-27.
Casaroo reviews each guide against current pricing, code, and insurer practice. Cost ranges are 2026
estimates that vary by region, size, and access — confirm specifics with a licensed professional.