Tips for Repairing and Working With Polybutylene (PB) Plumbing Pipe

Image Source / Getty Images

If your home still has polybutylene (PB) plumbing pipe, it is very likely to eventually fail. So it is a good idea to be proactive and replace it. Mobile homes in particular were often plumbed with PB tubing, and PB was also frequently used in standard stick-built construction during the 1970s and through the mid-1990s.

What Is Polybutylene Pipe?

Polybutylene pipe is a gray plastic tubing that was commonly used as a water-supply plumbing pipe between 1978 and 1995, at which time it was discontinued due to reports of pipes rupturing. In new construction, it was replaced by copper or more dependable forms of plastic pipe, such as CPVC and PEX.

Repairs to PB Piping Systems

Repairs to PB piping is very difficult since neither PB plumbing pipe nor the Quest fittings used to connect it are commonly made or sold anymore. The standard solution to problems, then, is to make repairs to the damaged sections of PB by transitioning to another type of pipe, or even to repipe the entire system.

There are a couple of options when selecting what type of fitting to use for the transition from polybutylene. The outside diameter of PB tubing is the same as for PEX, CPVC, and copper pipe so using push-fit fittings is one option you can use. The other is to use a specific transition fitting designed for transitioning between two different materials.


Do not be surprised if your plumbing uses PB piping (or another out-of-use type of piping), and it is not necessarily a bad thing to have to transition to a new material: Plumbers often must shift to a new material or piping if the current one is outdated.

Push-Fit Fittings

For accessible areas, push-fit fittings, often sold under brand names such as Sharkbite or Gatorbite, are the easiest way to make a repair.

Pinhole Leaks

When you find a small leak in a straight length of pipe under a mobile home or in other accessible locations, a push-on fitting can be used for a quick repair. Simply cut out the pinhole area and push on the repair coupling. Be sure to measure so you don’t end up cutting away more of the pipe than is necessary.

Replacing Shut-off Valves or Fixture Supply Tubes

Push-on shut-off valves are a good option for this repair, also. With new flex line water-supply tubes and push-on valves, you can change the water-supply lines to a toilet or faucet in minutes. Simply shut off water to the house, remove the old flex line from the fixture, cut back the PB pipe, push on a new shut-off valve, and connect a new flex line. Don’t forget to check for leaks several times after turning the water back on.

Replacing Large Sections of Pipe

When replacing large sections of pipe, you can also use push-on couplings to transition from PB to PEX, CPVC, or copper. It is a great way to break up an overall repiping project into segments if you don’t want to do it all at once. Connect to the PB pipe with a push-on coupling and run the new pipe from that point.

PB-to-PEX Transition Couplings

For inaccessible repairs, the best option is to use a transition coupling designed specifically to transition from polybutylene to PEX pipe. The PB-to-PEX transition coupling is made of brass and it compensates for the difference in inside diameter of PB pipe and PEX. This transition coupling also has two different crimp rings, one that is specifically meant to be used to secure the transition fitting to the PB pipe, and the other to secure the transition to PEX.

Leaks Inside Walls

A PB pipe or PB joint that is leaking inside a wall should be repaired by replacing the bad section with a non-PB pipe. The best solution is to use a transition coupling to convert that section to PEX. You can transition close to the leak, but if possible, follow the length of pipe and replace as much of the pipe as you can reach.

Valves Inside Walls

When installing or replacing a shower valve or other valve inside the wall, it is best to use a transition couplings to connect a new PEX riser to the PB system, especially if there won't be an access panel. This would be a good time, though, to install an access panel to make future work easier.

Washing Machine Valves

Push-on washing machine valves designed for PB are available but they can be difficult to find. A PB-to-PEX transition fitting is often the most convenient option. After transitioning to PEX, you can install a washing machine valves made specifically for PEX tubing.