While PEX plumbing may leach contaminants into your home’s tap water, limited research suggests it’s still safe to use
Generally more affordable, lighter, and easier to install than metal plumbing, PEX pipes are the perfect choice for your home, right? Not so fast. The product continues to grow in popularity, with reports showing an increase in PEX plumbing from 15% to 25% of all whole-home plumbing replacements from 2013 to 2015, respectively.
But as more consumers turn to PEX piping for its affordability and ease of use, it’s unclear whether PEX tubing may negatively impact water quality.
What Is PEX Piping?
PEX piping is a cross-linked polyethylene piping commonly used in home plumbing systems for heating, cooling, and water systems. In some instances, it’s also used to insulate electrical cables and wires. You can identify PEX pipes by the trademark red and blue colors most commonly found inside your home’s walls.
This type of piping is the least expensive among plastic pipes, costing just $0.45 per foot compared to the most expensive metal—copper pipe—at $2.55 per foot. Because it requires less energy to produce than metal pipes, it's become more common in homes and green building construction.
Are PEX Pipes Safe?
Researchers are examining the extent of PEX pipes’ impact on water quality, testing various brands of plastic pipes. Since there is so little research data on these pipes’ safety, some contractors hesitate to use PEX piping until they know more about its long-term impact.
From what is known, preliminary findings show different PEX brands affect water quality differently, and even pipes that pass safety tests may contain enough contaminants to affect water’s taste and smell. In fact, there are over 70 PEX pipe brands on the market, and studies showed that some of those PEX pipes have over 150 contaminants.
One of the most recent studies, conducted in 2021, tested water from eight different types of PEX pipe brands. They found that 62 chemicals leached into the water, with half of those organic compounds leached considered toxicological but not carcinogenic.
In other words, chemicals might get leached through your PEX pipes, and these chemicals may be toxicological to some extent. However, while PEX pipes may not be entirely safe, these findings are still not definitive; studies did not account for factors like the types of fittings used to secure the piping, disinfection byproducts, and any synergistic effects.
Potential PEX Pipe Problems
A few problems you might experience from your PEX pipes include:
Drinking water odors, such as that of gasoline, that might prompt you to avoid your water altogether
Poorer water quality from toxic chemicals and contaminants leaching into your water
Some leached chemicals may encourage bacteria growth in the pipes
Exposed PEX pipes that are vulnerable to UV rays and damage from cold climates and must be kept indoors, underground, or in the walls of your home
Toluene, a solvent used for plastic resin synthesis, often causes odors that reach a detectable level. The level of solvent, however, does not exceed health standards. So, while the gasoline-smelling water may cause homeowners to wrinkle their noses, it’s generally safe to use.
How To Prevent PEX Water Quality Issues
PEX piping is still relatively new in the United States. Contractors began installing it about 35 years ago, with California last to approve its use; according to California State Pipe Trades Council, it wasn’t until 2018 that California completed its review on the safety of PEX piping.
The state still has concerns regarding the safety of PEX pipes and has implemented provisions to protect residents from potential issues. Until researchers have definitive answers, California urges homeowners with existing PEX piping to filter drinking water from the tap to ensure no issues with the quality of water coming from PEX water pipes.
In addition, you might want to consider flushing your piping system regularly. This is because any contamination that may occur builds up as water stays stagnant in the piping. Even a three-day vacation without using your taps can cause a chemical build-up in the water.
When installing PEX piping as part of new construction, some states (such as California) mandate that contractors must flush the pipe system for at least two minutes, let the system stand for no less than one week, and then flush the system long enough to empty the contained volume of water.
PEX Pipe Alternatives
If you’re concerned about existing PEX pipes in your home and want to replace them, or if you’ve changed your mind about purchasing PEX pipes, there are a handful of alternatives. Let’s look at the most common types of materials used for household plumbing and why they may or not be a good fit for you.
Copper pipes have withstood the test of time for over 75 years, but this doesn’t mean that they’re the best alternative to PEX piping. For one, you’ll need to replace them more frequently; PEX piping can expand during cold weather, making it more suitable for places where winterization is necessary. Copper is also much more expensive, as mentioned previously, costing nearly six times as much as PEX piping.
However, some installers have more experience and trust in installing traditional copper piping. This option can also withstand UV rays and may be more appropriate for hotter climates where the sun might pose a threat to piping and freezing is rare. Overall, PEX pipes are more sustainable, affordable, and long-lasting, while copper pipes are more prone to corrosion and small leaks that are more costly to replace.
Another alternative to PEX pipes and copper pipes is PVC. Also known as polyvinyl chloride, this thermoplastic is designed for household plumbing. It has a long lifespan, lasting for as long as 50 to 70 years, approximately 10 to 20 years longer than PEX piping.
A major pro to PVC piping is that it’s safe to use outdoors, so long as it’s coated with water-based paint when exposed to sunlight. You can also recycle PVC piping, making it relatively more environmentally friendly.
On the downside, PVC is more likely to leak or crack during a freeze. It also can’t tolerate temperatures greater than 140 degrees Fahrenheit. If you wish to use PVC piping for hot water, you’ll need to opt for CPVC.
Chlorinated polyvinyl chloride (CPVC) is closely related to PVC, except it’s made out of chlorinated PVC resin. This means that, compared to PVC, CPVC piping is more resistant to temperature changes; it can sustain temperatures of up to 200 degrees Fahrenheit. The temperature resistance comes at a price, though. You’ll have to pay six times as much for this option compared to PVC.