PEX may leach contaminants into your water, so most people stick to copper supply lines
PEX is lighter and more affordable than traditional copper, and it’s less likely to leak.
Most research suggests that PEX isn’t ideal for drinking water.
Filtering water from PEX lines makes it safe for consumption.
Most homeowners stick to other pipe options for water supply lines, like copper.
As more people turn to PEX piping for its affordability and ease of use, asking if PEX is safe for drinking water is important. Unfortunately, it’s unclear whether PEX tubing may negatively affect water quality, and most research suggests that it’s not the ideal material to deliver drinking water. We’ll discuss its safety and some alternative materials in this guide.
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 between $0.50 and $2.00 per foot, depending on the thickness. Compare that to the most expensive metal—copper pipe—at $2 to $8 per foot, and it’s easy to see why PEX has risen in popularity. Because it requires less energy to produce than metal pipes, it's become more common in homes and green building construction.
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 for water supply lines to taps until they know more about its long-term impact. Most are comfortable using PEX to run to appliances and fixtures that don’t deliver drinking water, including the following:
Bathroom sinks
Showers and tubs
Hose bibs
Washing machines
Dishwashers
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 and published by Science Direct 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—basically, toxic—but not carcinogenic, or cancer-causing.
In other words, chemicals might get leached through your PEX pipes, and these chemicals may be toxic 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.
A few problems you might experience with your PEX pipes include the following:
Drinking water odors, such as that of gasoline, might prompt you to avoid your water altogether
Decreased 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.
That doesn’t mean all of the leached chemicals are safe for consumption, though. If you’re concerned about water quality, you can always call a water specialist near you to come test your water.
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.
It’s worth noting that you’ll need a standalone type of water filtration system, like a filtration pitcher or a filter that connects to your faucet. A whole-home water filtration system will only treat the water before it reaches the PEX, which can still leave you with unwanted chemicals. You might also want a whole-home filter to avoid hard water stains on your dishes or soap scum build-up in showers and tubs.
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.
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, especially if you have hard water; PEX piping can expand during cold weather, making it more suitable for very cold climates, and it won’t corrode in response to minerals in the water like copper will. Copper is also much more expensive, as mentioned previously, costing about six times as much as PEX piping per linear foot.
Some installers have more experience and trust in installing traditional copper piping, so even barring the concern with water contamination, they’ll resort to copper because they’re more familiar with it and trust its durability. Some may still shy away from copper, though, if they test for hard water and determine that the material won’t last long due to corrosion.
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.
Consider the advantages and disadvantages of PEX vs. copper piping when installing or replacing pipes in your home.
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 life span, 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 a bit 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, so you can use it as a supply line for hot water. The temperature resistance comes at a price, though. You’ll have to pay six times as much for this option compared to PVC.
ABS stands for acrylonitrile butadiene styrene, which is a black plastic pipe material that contractors and plumbers most often use for drain lines or drain-waste-vent (DWV) systems. ABS is similar to PVC in structure, although it stands up to pressure better and can resist higher and lower temperatures without cracking or shattering. As such, it’s also common to see ABS pipe in underground plumbing applications, like sprinkler systems or cisterns, especially in extreme climates.
ABS contains Bisphenol A, more commonly referred to as BPA. Some research suggests that BPA is a carcinogen, although the official stance of the Centers for Disease Control and Prevention is that it likely isn’t cancer-causing. Still, most people avoid exposure to BPA to be safe. Some homeowners with ABS supply lines will drink bottled or distilled water instead, or hook up a filtration system on their faucets. Distilled and purified water are always safer options if you have ABS pipes or another plastic pipe material.
For that reason, ABS pipe can serve as an alternative for PEX pipe in some cases, but it’s not the best option for delivering drinking water unless you pass the water through a good filtration system, as is recommended with PEX.
