Do you have polybutylene water pipes in your home? Or are you considering buying a house with poly and want to know more?
You are in the right place. In this article, I will go over the origin, history, problems, and evolution of polybutylene plastic piping. The installation of poly water pipes stopped in 1995 in the USA due to numerous leaks and lawsuits.
In this guide, we will go over…
Let's get started with this guide on poly!
What Is Polybutylene?
Polybutylene is a type of plastic pipe that was manufactured for water supply in residential homes from 1978 to 1995. 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 near 20 year period. The last year that you will likely find a home with poly is 1996 due to built up supplies. Poly was also used for main water lines — from the home to the street — in single family homes.
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.
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. 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.
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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Poly was originally made under the brand name “Qest”, and it was marketed to builders as a much cheaper alternative to copper piping.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.
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.
How & Where Did Poly Leak?
In the beginning of the poly revolution, 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.
The biggest change in the installation of poly was by replacing the use of plastic (acetal) fittings to metal fittings. The metal fittings were in the form of copper (or brass) AND they changed the compression bands from aluminum to copper. These changes at first seemed to work, and the leaks decreased.
Polybutylene with metal fittings and rings are undoubtedly the “least worst” type of poly piping installation method. However, even these metal fittings began to fail. And leaks were also showing up elsewhere along the pipe — not just at the fittings.
What we know now is that polybutylene 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.
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 bursted pipe and significant home damage.
Read Also: The Best Water Pressure Booster Pumps
What Are The Signs of a Home With Poly?
As a home inspector who has seen numerous homes with poly piping, the most obvious sign (besides the actual pipe) that a property has poly is numerous ceiling water stains. During inspections, I always check moisture stains with a moisture meter to see if it's active. From first hand experience, the homes with the most water stains were almost always homes with defective polybutylene water pipes.
Even if an owner completely replaces the poly piping, it is very difficult to remove the signs of every water stain. The contractor would be extremely good to leave no evidence of patching or paint cover ups — it’s almost impossible. When I inspect a home, I’m looking at the ceilings with a high powered flashlight, and I can detect even very minor imperfections.
How Do Plumbing Leaks Cause Damage?
Leaking poly piping can cause sizable damage to a home. When water leaks onto framing and drywall, it can result in mold growth. Unlike in an HVAC system where you can install a UV light sanitizer to stop mold growth — there is no way to inhibit microbial growth within a wall cavity that goes undetected.
If it is a slow leak, you may never realize that mold is growing, and mold spores spread throughout the home. 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.
I did one home inspection on a home in Bowie, Maryland that ruined an entire finished basement. There was a small leak at a pipe in the basement, and it steadily released water while the homeowner was on vacation in a different country. Unfortunately, the owner made the problem much worse because he turned off the air conditioning system which has a dehumidifying effect.
Well, when he got home, the entire basement was covered in mold — the ceiling, the walls, and even the floor. The entire basement would have to be demolished and re-done, likely at a cost of at least $40,000. And this was all from one small plumbing leak (and turning off the a/c during the peak of summer).
Don’t even get me started on how water can attract termites!
How Did Poly Change Over Time?
There were three main developments with poly, and each was introduced because of problems with leaking.
- Plastic fittings with aluminum compression bands
- Copper (or brass) fittings with copper bands
- The manifold or “home run” system
Plastic Fittings & Aluminum Rings
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.
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.
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…
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.
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. In fact, the system became so easy to install, that plumbers even trained non-plumbers to install the manifold poly system.
However, this lead to something else very interesting.
Because the manifold system used flexible poly piping, this gave the piping a very cheap and flimsy look as it was strapped to the ceilings and walls. Builders wanted to hide this cheap and undesirable look. And that’s when they started installing copper stub outs to hide poly.
Copper Stub Outs (Hidden Poly)
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. Clever no?
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.
Watch Out For Poly Feeder Lines To Sinks
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.
Pro Tip: Don’t confuse poly with PEX which is also commonly used in feeder lines.
The Main Water Line (A Commonly Overlooked Issue)
Most real estate agents are now familiar with the problems with polybutylene piping in the home’s domestic water system — but most are unaware that a poly main water line can also be an equally hazardous problem (if not more).
A poly main water line in my area always 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.
The main water line is as susceptible to chlorine as the smaller diameter branch piping inside the home. 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.
What Happened To The Class Action Lawsuits?
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.
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.