Grey pipe, 1978 to the mid-90s: how to tell, and what to do

How to tell whether you have it

You are looking for a flexible plastic supply pipe, half inch to one inch, most often grey. It was also made in white, silver, black and blue. It was never used for drain, waste or vent, so anything grey and flexible carrying pressure is a candidate and anything under a sink carrying waste is not.

The definitive marker is the stamp. Polybutylene is marked PB2110, which is its ASTM material cell classification. If you find that printed along the pipe, the question is settled.

Where to look, in order. At the water heater, where supply lines are exposed. At the meter and around the main shutoff. Under sinks and behind toilets, where a stub comes out of the wall to a fixture stop. In an attic, where a run may cross open framing. You are not opening anything up. You are reading printing on a pipe.

Look at the fittings as well as the pipe. Early systems used acetal insert fittings, sold under the Celcon name, with aluminum or copper crimp rings. Later systems used copper insert fittings. The acetal fittings and the aluminum rings were the dominant failure point in the whole system, so what is on the ends matters as much as what is in the middle.

Why it fails, and why the disinfectant matters here

The failure mechanism is chemical, not mechanical. Research from the University of Illinois at Chicago found that certain disinfectants react with polybutylene and cause it to flake apart. Micro fractures form on the inside wall and deepen outward until the pipe breaches. Failures concentrate at stress points, which means fittings and bends, and a breach can present as a burst with very little warning.

That is why the disinfectant in your water is not a footnote. St. George disinfects with chlorine rather than chloramine, and the 2024 water quality report shows a chlorine residual measured between 0.10 and 1.19 ppm in the distribution system. Whatever else that residual is doing, it is doing it continuously, every day the pipe is in service, from the inside.

Pipe manufacturers argued at the time that most leaks came from joints and unions installed badly, not from the material. Both things can be true and neither helps you, because the practical consequence is identical: the failures happen at fittings, and you cannot see them coming.

That is the hardest part of this material to accept. The deterioration happens from within and cannot be detected without turning the water off and dismantling the pipe. There is no test, no scope, no meter reading that tells you how much life is left in a polybutylene system. An inspection tells you what material you have. It does not tell you when.

The national class actions over this material produced payouts approaching a billion dollars, decades ago. That is history rather than a plan for your house.

What to do about it

The published remedy has not changed: the only long term solution is to completely replace the polybutylene plumbing throughout the building. Spot repairs are a treadmill. Every repair fixes the one fitting that failed, in a system where the next failure is somewhere else, and each repair costs a wall opening.

That does not mean you have to repipe this month. It means the decision is a repipe decision, not a repair decision, and it should be made deliberately rather than at 11 p.m. with a wet ceiling. In the meantime, two things are worth doing today. Find your main shutoff, tag it, and turn it once so you know it turns. And decide in advance who is calling whom if a fitting lets go while you are out of town.

PEX, copper, or CPVC

There are three realistic materials for a repipe, and the right answer here leans hard toward one of them for a reason that has nothing to do with preference.

PEX comes in three types. PEX-A has the highest crosslink density, is the most flexible, and has thermal memory, so a kink can be repaired with a heat gun rather than a coupling. It uses cold expansion fittings under ASTM F1960, where the pipe and a reinforcing ring are expanded and shrink back onto the fitting, which leaves the largest effective inside diameter of the common systems and the least flow restriction. It is the most expensive. PEX-B is stiffer, generally carries higher oxidative and chlorine resistance ratings in published product listings, and uses copper crimp rings under ASTM F1807 or stainless cinch clamps under ASTM F2098 over insert fittings. Insert fittings restrict the inside diameter more than expansion fittings do. It is the volume product. PEX-C is the least common and the most prone to kinking.

Copper Type L has a 50 year plus service life, is rigid, is fire resistant, has no permeation concerns, and holds its value at resale. Its failure modes are its own: pinhole pitting corrosion, erosion corrosion at elbows on high velocity recirculation loops, and Type I pitting initiated by flux residue left at soldered joints.

CPVC is the cheapest material and the fastest to install, and it carries two problems that matter locally. The first is environmental stress cracking. Many thread sealants, cutting oils, spray foam insulations, firestop caulks, and even some marking pens will initiate a crack in CPVC that fails months later, with nothing visible at the time of installation. The second is temperature derating.

The attic argument

In slab on grade houses, water lines run either under the slab or through the attic, and on a repipe they go through the attic. That is the whole ballgame for material selection.

CPVC is rated 180°F at 100 psi, and its pressure rating falls steeply as temperature rises. PEX carries published ratings of 200°F at 80 psi, 180°F at 100 psi, and 73°F at 160 psi. Now put that in this climate. St. George recorded 98 days at or above 100°F during 2024, an all time high of 117°F, and back to back hottest Julys on record in 2023 and 2024. Attic space is unconditioned space sitting above that.

So for attic distribution here, PEX is the materially better suited product, and that is an engineering reason rather than a habit. It is also why we insulate attic runs and route them beneath the ceiling insulation blanket wherever the geometry allows, because the same attic that is brutal in July sees roughly 60 mornings a year at or below freezing.

Ask about the fittings, not just the pipe

The lesson polybutylene actually taught the trade was not about plastic. It was that a piping system fails at its connections, and the connections are the part nobody looks at or asks about.

So on any repipe quote, ask which fitting system is going in your walls: cold expansion F1960, copper crimp F1807, or stainless cinch F2098. Ask what the fittings are made of. Get it in writing on the estimate, and photograph a few connections before the drywall closes. That single set of photographs is worth more than any warranty conversation you will have later.

One clarification about CPVC, since it usually comes up next to polybutylene in the same sentence. There is no industry wide recall of CPVC potable piping. Its failures trace to chemical incompatibility and to age embrittlement, not to a manufacturing defect, which is a different problem with different implications for how it is installed and what it is installed next to.

What a repipe actually involves

It is a demolition job with plumbing in the middle of it, and knowing the sequence in advance removes most of the anxiety.

A manifold position is chosen, usually in the garage near the softener loop and the main shutoff. Drywall is opened at each fixture wall and at the manifold. New lines are run, either as home runs from the manifold or as a trunk and branch layout. Each fixture gets new stops. The system is pressure tested and inspected. Then the openings are patched, textured and painted, which is normally a separate trade from the plumbing.

The plumbing is the shorter half. The finish work behind it is what people remember, so ask who is doing it, when they start, and whether texture and paint match is included or excluded, before anyone opens a wall.

Water is off during working hours, so plan for that. And this is a permitted, inspected job. The inspection is the only independent look anyone takes at the pipe before it disappears behind drywall.

More under plumbing

• Your backflow test notice, explained
• A pipe broke in the wall of your condo. Who pays?
• What St. George water does to a water heater