What Is Polybutylene Pipe? (Identify, Lawsuits, Cost)

Are you interested in learning about polybutylene water piping?

Polybutylene pipe was installed in millions of homes in the 80’s and 90’s, but we now know that it is a defective water pipe.

Polybutylene is prone to fractures (both large and small) which eventually leads to water damage in a home. I have inspected numerous homes with polybutylene piping, and they typically have ceiling water damage all over the home.

In this HomeInspectorSecrets.com guide, I will go over…

  • What is polybutylene piping?
  • How to identify polybutylene plumbing (don’t confuse with PEX!)
  • The three main types of PB pipe systems
  • The danger of polybutylene main water lines

Keep reading to learn all about polybutylene piping and how to identify it!

What Is Polybutylene Pipe?

Polybutylene is a type of plastic pipe that was manufactured for water supply in residential homes staring in 1978. 

Unfortunately, this plastic piping is notorious for micro fracturing, split pipes, and subsequent home damage (and settled class-action lawsuits).

It is estimated that about 7 to 10 million homes in the U.S. had poly installed during this period.

Polybutylene was also used for branch piping throughout the home which goes to each fixture as well as for main water lines — from the home to the street. 

When Was Polybutylene Plumbing Banned?

Polybutylene pipe was banned in 1995 and manufacturing was no longer allowed in the United States.

The last year that you will likely find a home with poly is in 1996 due to built up supplies.

The main reasons for polybutylene getting banned was a series of class action lawsuits against the suppliers and manufacturers of polybutylene pipe.

Read Also: Tips & Traps When Buying A Home

How To Identify Polybutylene Pipe?

Polybutylene usually has a grayish-blue appearance, but it can also come in silver, cream, or black — one region of the country typically has the same color.

In my neck of the woods (the D.C. area), poly usually has the typical bluish-gray appearance.

One surefire way of identifying polybutylene is to look for the PB2110 mark stamped somewhere on the pipe.

polybutylene pipe with identification stamp

Besides copper piping (which should be easily identifiable), you don’t want to confuse poly with other plastic piping such as PEX, CPVC, or PVC which are very common plastic water pipes.

PVC (a common white pipe) is only used for drain, waste, and vent piping and is not used for potable water.

polybuytlene pipe with blue-gray color

PEX piping is usually red (for hot water) and blue (for cold water), but it can also be different colors and even clear-colored. PEX is also stamped with “PEX” somewhere along the pipe.

CPVC is a cream colored pipe with a yellow stripe along it’s length which is very common in newer homes due to the high cost of copper.

How Much To Replace Polybutylene Pipe?

The cost to replace polybutylene plumbing typically costs $2,500 to $20,000 depending on the number of fixtures, size of home, drywall damage repair, and the type of new piping.

Companies that replace polybutylene are called re-piping specialists, and they aren’t your typical plumber. These re-piping companies typically charge on a per fixture basis, but there are other factors such as if they will be repairing all of the drywall holes.

Also, if the home has a crawlspace, the cost to replace polybutylene pipe can be much cheaper because there is easy access to most of the piping.

If you want to replace the piping with copper, the cost will also be significantly more.

Polybutylene pipe is usually replaced with PEX piping or CPVC piping.

Why Was Poly Installed In Homes?

Poly was originally made under the brand name Qest, and it was marketed to builders as a much cheaper alternative to copper piping. As far as builders knew, poly was a great material, approved by building codes, and it had excellent resistance to freezing temperatures.

Easy Installation

Not only was poly significantly cheaper than copper, it could also shave days or even weeks off from a whole house plumbing installation; a very big advantage for builders.

In fact, installing poly was so easy to install that some plumbers even trained non-plumber employees to install it in homes.

Plumbers could also stop carrying around acetyl or propane tanks to each job site that was needed for sweating copper. The installers basically just needed one crimping tool to get the job done that saved a tremendous amount of work.

Rather than being soldered together like in copper (or glued together as in CPVC), poly was fastened together by using compression bands called “crimping”. Modern PEX piping still uses this compression/crimping style of installation. Poly was also much lighter than copper, so it was easier to carry to the job site.

At the time, poly manufacturers told builders and plumbers that it had a lifetime expectancy of 50 years, which we later found out to be far from the truth. On average, it only took about 12 years for problems with leaking poly pipes to show up.

Read Also: My Top Tools For Home Inspecting

Where Does Polybutylene Pipe Leak?

During the early years of polybutylene installations, the majority of leaks happened at the fittings.

It was theorized that these leaks were mainly due to improper installation, exposure to UV light, improper storage, bad water chemistry, and other issues. This lead to changes in the fittings to try to solve the problems being reported with poly.

Polybutylene manufacturers tried replacing the use of plastic (acetal) fittings to metal fittings. These changes at first seemed to work, and the leaks decrease, but a few years later, even these metal fittings began to fail. 

And leaks were also showing up elsewhere along the pipe — not just at the fittings.

Unfortunately, it is impossible to know exactly where poly leaks will occur because it is an largely invisible process. The small cracks and flaking occur on the INTERIOR of the water piping, and these cracks eventually work their way outwards….where the leaks finally appear.

These leaks can occur gradually and slowly, or they can happen suddenly with a burst pipe and significant home damage.

Why Did Polybutylene Pipes Leak?

Polybutylene was prone to leakage because it was discovered that the pipe deteriorates in the presence of chlorine and other disinfectants in the public water supply.

When poly was introduced in the late 1980’s, we simply did not know how this piping would stand up to chlorinated water.

Currently, we have advanced testing standards for the structural strength of plastic piping such as PEX and CPVC in the presence of chlorinated water that polybutylene was not subjected to in the 1970’s.

Read Also: The Best Moisture Meters (Find Hidden Leaks)

water damage on ceiling

How Do Polybutylene Piping Leaks Cause Damage?

Polybutylene pipe can cause damage to a home through drywall damage, wood damage, and even mold growth. 

Mold Growth

Leaking poly piping can cause sizable damage to a home through mold growth.

When water leaks onto framing and drywall, it can result in mold growth not only inside the walls — but the spores can be sent into the HVAC duct system. And the water leaks from PB piping are usually unseen, and can fester for years hidden inside the walls.

Once you have detected any leaks, it is important to immediately remove all visible mold and to replace the poly piping.

A home’s furnace can act as a central location to send mold spores throughout the entire home.

Wood Damage

Besides mold growth, leaking water pipes can damage the home’s wood framing, appliances, flooring, and furniture. 

Just one hidden leak may cause structural weakening of the home’s framing. Wood damage may result in sagging joists (and flooring) or other structural issues.

And if you add the damage resulting from several small leaks together, that alone can equal the costs of replacing the entire home’s piping; anywhere from $10,000 to $20,000 or more (depending on the size of the home).

One sudden and large pipe burst in a home — let’s say while you are on vacation — can lead to tens of thousands of dollars in damage.

Drywall Damage

Leaking polybutylene pipe can cause significant damage to drywall.

The leaking PB can drip onto drywall for a long time without anyone noticing, and then by the time the ceiling or wall buckles or bows out, it is too late.

The drywall will need to be completely replaced.

How Did Polybutylene Change Over Time? (5 Key Developments)

There were numerous developments with polybutylene, and below are a few of the important changes to PB piping:

  1. Plastic Fittings With Aluminum Compression Bands
  2. Metal Fittings With Copper Rings
  3. The Manifold Or “Home Run” Poly System
  4. Plastic Fittings With Aluminum Compression Bands
  5. Polybutylene Pipe ‘Feeder Lines’ To Sinks

1. Plastic Fittings With Aluminum Compression Bands

In the early years of poly, the pipes were connected with numerous acetal (plastic) fittings that were usually the same color as the poly piping. The very first plastic fittings were compression-type fittings also known as “grip” fittings.

Later on, plastic fittings were crimped to the poly pipes using aluminum rings.

There were approximately 10-20 plastic fittings from one plumbing fixture to the main water line; many possible points of failure.

Unfortunately, leaks occurred with significant damage to homes across the U.S.

polybutylene piping with compression fittings
polybutylene pipe with acetal fittings

2. Metal Fittings With Copper Rings

The next development occured when installers scrapped the problematic plastic fittings in favor of copper/brass fittings with copper rings.

This greatly reduced the problem of leaks at the fittings — at least for a while.

polybutylene pipe with copper fittings
polybutylene pipe with copper fittings

Unfortunately, leaks kept occurring, and lawsuits were brewing. Poly has been found to leak and rupture at potentially any location in the pipe, a plumbing mine field.

A study at the University of Illinois has shown that microfractures can occur at any point of the water pipe, and it can break or rupture without warning.

Nevertheless, poly went one step further in technological development…

3. The Manifold Or “Home Run” Poly System

The manifold was also an “improvement” on the poly system. The manifold or home run system simply means that there is a central location or “manifold” where every plumbing fixture directly connects to it.

So each plumbing fixture is isolated and doesn’t share water piping with any other fixtures. Modern PEX piping still commonly uses the manifold type of system.

polybutylene pipe manifold system
polybutylene pipe manifold system

This means that there are fewer fittings needed for each plumbing fixture. Without the manifold system, there would be about 20 fittings just for one plumbing fixture.

By using the manifold, the number of fittings was reduced to around 4-5.

With fewer fittings, it meant less opportunity for leaks. In addition, the manifold could be easily monitored for leaking — a central area where the fittings are located.

Besides reducing the areas of possible leaks, it also greatly reduced the amount of time to install poly because of the fewer fittings. With manifold systems, a more flexible version of poly pipe was installed, and it typically came in rolls of 20 to 100 feet long.

Read Also: The Best Hot Water Recirculating Pumps (Instant Hot Water)

4. Copper Stub Outs To Fixtures (Hidden Poly Piping)

The copper stub outs (end piece copper sections) connect the plumbing fixture and go just to inside the wall cavity where it is connected to the poly. So if you looked under a sink, all you would see is copper!

The actual poly pipe is hidden behind the wall. As a home inspector, since I can’t drill holes in walls, all I can say is that the home appears to have copper piping even if there is poly hidden inside.

5. Polybutylene Pipe ‘Feeder Lines’ To Sinks

polybutylene feeder pipes under sink

If you have a house built in the 1978 to 1996 time period, and even if you don’t have poly in your domestic water pipes, I would still check under all of the sinks for the supply lines. I still commonly find poly supply lines to bathroom sinks.

These smaller diameter poly pipes are also susceptible to chlorinated water and can be ticking time bombs.

If you are home, and it springs a leak, it may not be such a big issue. But what if a homeowner is on vacation? Just one small rupture in a sink feeder line can cause an untold amount of damage.

Poly Feeder Lines

The Polybutylene Main Water Line (A Commonly Overlooked Issue)

Most people are unaware that main water lines can also be made out of polybutylene and are prone to leaking and rupturing just like the home’s branch piping.

A poly main water line typically has an intense blue color, and is easily distinguishable from copper or HDPE. HDPE is high density polyethylene which is always a black color. 

Almost all new homes now use HDPE for the main water line.

main water line polybutylene pipe

The main water line is as susceptible to chlorine as the smaller diameter branch piping inside the home.

Potential Foundation Damage

The potential damage with a ruptured main water line is a little different than inside a home. Imagine you are on vacation, and your main water line breaks. A massive amount of water is going to be deposited near the house.

As you might assume, water and foundations don’t mix.

As a home inspector, we are always harping about fixing the grading around the foundation (the ground should slope away from the home), and fixing poorly draining downspouts.

If hundreds of gallons of water are saturating the ground by the house, this increase in pressure can literally cause the foundation of the home to buckle — a phenomenon known as hydrostatic pressure.

So instead of water damage to the floor and drywall, a bursted main water line can literally move the entire house!

The costs of fixing a foundation problem like this could be astronomical.

main water line polybutylene pipe
main water line polybutylene pipe with sharkbite fitting

What Happened To The Class Action Lawsuits For Polybutylene Plumbing?

There were two main class-action lawsuits in the 1990’s, Spencer Versus DuPont and Cox Versus Shell.

Shell and DuPont were two of the largest manufacturers of polybutylene. They both settled with the courts and have agreed to fund a settlement that has totaled around one billion dollars.

Both of these settlement funds have been depleted, and homeowners are now on their own.

screenshot of closed settlement funds for polybutylene piping

What’s The Bottom Line On Polybutylene Pipe?

Polybutylene was touted as an incredible plumbing invention when it first came out, but we now know it has come up very short (and very wet).

Like many construction product defects, the “final word” on the quality of a product can take many years and lawsuits to bear fruit.

I hope this guide has given you some quality information on polybutylene and some of the most important things about it’s history and use.

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