Polybutylene Pipes in Mobile Homes: What Stanton Owners Should Know

By Cypress CA Plumber · October 16, 2026

If your mobile home or condo was built between the late 1970s and mid-1990s, there may be gray plastic pipe under the floor worth checking.

Stanton has more mobile home parks than you might expect for a city of its size - several along Katella Avenue, Western Avenue and Beach Boulevard date back to the 1960s and early 1970s, and homes have been replaced and upgraded in them over the decades since. Many manufactured homes built between the late 1970s and the mid-1990s share one plumbing issue: polybutylene pipe.

What polybutylene is

Polybutylene (often shortened to PB) is a plastic water supply pipe that was widely installed from about 1978 to 1995. It was inexpensive and easy to install, which made it especially popular in manufactured homes, as well as many site-built homes and condos of that era. Production stopped in the mid-1990s after widespread reports of failures and a large class-action settlement.

How to spot it

• Color: usually gray, sometimes black or blue
• Markings: often stamped "PB2110" along the pipe
• Where to look: under sinks where the line comes out to the shutoff, at the water heater, and under the home behind the skirting
• Fittings: early systems used plastic fittings with aluminum crimp rings; later ones used copper rings or brass fittings

Don't confuse it with PEX, the modern plastic pipe, which is usually red, blue or white and stamped "PEX."

Why it fails

The generally accepted explanation is that oxidants in treated water, such as chlorine, gradually react with the plastic and the fittings, making them brittle from the inside. The pipe can crack, and the fittings - especially the early plastic ones - can split or leak. Failures often happen without warning, and because manufactured home plumbing runs under the floor, a leak can soak insulation and the underbelly for a long time before it's noticed.

Signs of trouble

• Damp or soft spots in floors
• Water dripping from the underbelly or pooling under the home
• A water bill that rises without explanation
• Visible white flaking or cracks on gray pipe
• Low pressure or leaks at fittings near the water heater

Your options

Leave it and watch it. There's no law requiring polybutylene to be replaced, and some systems last longer than others. If you keep it, check it regularly and know where your shutoffs are.

Replace failing sections. Fixing a single leak with modern fittings works in the short term, but the rest of the pipe is the same age and material.

Repipe. Replacing all the polybutylene with PEX or another modern material is the permanent fix. In manufactured homes, the work is usually done from underneath, which can make it more straightforward than repiping a slab home. See PEX repiping.

If you're buying a mobile home

• Ask the year of manufacture - it's on the data plate and title paperwork
• Look under sinks and at the water heater for gray pipe
• Ask if the home has been repiped and get any paperwork
• Check under the home for signs of past leaks
• Read the park's rules on who's responsible for which plumbing and what approvals are needed for work

Not just mobile homes

Polybutylene was also used in some site-built homes, condos and townhomes of the same era across Orange County. If your Cypress, Garden Grove or Westminster condo dates from the 1980s or early 90s, it's worth a look too. See our post on what your home's age says about its plumbing.

Water heaters in manufactured homes

While you're checking the pipes, look at the water heater. Manufactured homes need water heaters approved for that use, with specific venting, and tanks still need proper earthquake strapping. See water heaters.