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Polybutylene Pipes | What Is the Main Problem?

If your home was built or remodeled between the 1970s and the late 1990s, it’s possible your pipes are made from polybutylene. Those odds increase if you live on the sun belt, where they were most commonly used.

If you know or suspect you have polybutylene pipes, you might be wondering why there’s such a fuss about getting them replaced. Despite seeming to be ideally suited for water supply lines, the material is simply not suited for long-term water exposure.

The problem with polybutylene water supply pipes is that the plastic responds negatively to the chlorine contained in the water supply. The resulting chemical reaction causes the pipes to scale, flake, and chip. Pipes can crack and leak or even burst without warning.

Polybutylene Plastic Reacts With Water Additives

The primary issue with polybutylene plastic is that it reacts with certain materials that we add to our water. Of these additives, chlorine is the most commonly recognized to cause an adverse reaction with polybutylene plastic.

We add chlorine to our water supplies for a good reason, so we can’t just take it out. The reason is that it’s a disinfectant! By chlorinating our water, we prevent disease-spreading pathogens from making us ill by damaging their cell walls and “inactivating” them. 

Not only is chlorine effective at disinfecting, but it’s easy to chlorinate our water supplies and it’s considered safe for human consumption at the levels we use it.

Chlorine pods beside the pool

Here lies the problem, however. While chlorine is safe on its own, its reaction with the polybutylene pipes causes scaling, flaking and chipping, and general weakening of the pipes.

Scaling, or mineral buildup, causes an issue because it can narrow the pipes and increase the pressure of the water flowing through.

Bits of the piping itself will flake away alongside the scale, meaning that the pipes actually end up becoming thinner over time.

As the pipes thin out, they become more brittle. They will flake off more and more, and may develop hairline fractures or cracks from the inside out. Over time, these cracks will continue to develop and cause water leakage. 

Plastic Flakes in the Water Supply

As mentioned, polybutylene can chip and flake when reacting to chlorine. While this is, of course, not good for your pipes, it’s bad for you too. Those bits of plastic don’t just disappear—once they’re created, they’re in your water supply!

If you have polybutylene piping and you are drinking the water that comes through it, it’s likely you’re ingesting tiny bits of plastic or microplastics.

Ingesting a small amount of microplastics isn’t likely to be very harmful. But we know that over time and in larger amounts, they do put stress on and cause harm to the body. 

Weakened Plastic Is Prone to Leaks and Bursting

Of the two big problems with polybutylene pipes, we’ve already covered the risk of microplastic consumption. Now, let’s take a look at the damage that your home can sustain once your pipes begin to leak.

Cosmetic Water Damage

The first—and probably least concerning—problem water damage can cause is a cosmetic issue. 

If water leaks out of your pipes you may see staining or discoloration develop on your walls, floors, or ceiling. In addition to this discoloration, paint may blister and swell off the walls or ceiling if there is enough to soak through.

Further, if there’s enough water to soak through, any nearby furniture may also sustain damage!

Some of these issues, like discoloration, can be fixed with a quick repaint once the leak is resolved, but more severe cosmetic damage may require more extensive repair work like removal or replacement.

Structural Water Damage

If there is a big enough or sustained water leak, the problem will become more than cosmetic—the structure of your home may be at risk.

The structure of most homes is made primarily of wood, which is a material that doesn’t exactly stand up to water too well.

Wood is a porous material, making it great at soaking up water. This can lead to several things. One is the displacement or shifting of the wet beams. The other issue that is likely to result is the development of mold or rot.

Mold in white walls

Shifting House Foundations

As mentioned above, wood can become displaced when it soaks up water. Wet wood may expand as it soaks up liquid or become slightly flexible, and this change in size and stiffness can create strain on the studs, joists, and other wooden beams that make up your home’s framework.

This strain and swelling will cause the pieces to shift. This can cause parts of your home to become less stable, sag, or even collapse, depending on the severity of the damage.

Interrupted Water Supply

If your pipes develop cracks and begin leaking, you might notice a drop in water pressure. Depending on the leak’s size, this may be more or less noticeable.

Worst case, your water supply can be completely interrupted!


Polybutylene pipes are not outlawed in the USA, but in the late 1990s, manufacturers stopped selling to US markets. They are outlawed in Canada. But neither of these North American countries require you to replace your existing polybutylene pipes. Yet, you should definitely consider it.

The cost of replacing polybutylene pipes certainly isn’t cheap. Depending on the size of your home, how complex the job is, and how much needs to be replaced, the job is likely to run you anywhere between $1,000 to $15,000!

Granted, if you suspect you have polybutylene pipes, the cost of having them replaced upfront will be a lot cheaper than waiting for the inevitable leakage.

Cost of replacing polybutylene pipes in your house

It’s important to note that just because your pipes look fine now, they may not be since polybutylene deteriorates from the inside out; you have no idea how close it is to failure.

When they fail, you’ll not only have to pay for pipe replacement, but it’s likely you’ll have water damage to deal with too.

Water damage on top of pipe replacement could run you an additional several hundred to several thousand, depending on the severity. 


Since polybutylene pipes are a known liability, it’s extremely unlikely they will be covered by homeowner’s insurance. That means if you know or suspect your pipes are polybutylene, their existence in your home is a liability to you too!

If your home does have polybutylene pipes, your best bet is again, replacement before the damage can be done. It can’t hurt to see if you can get help covering the costs under your home warranty or your homeowner’s policy, however. 


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