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Community and Q&A

PEX tubing

Arlene DiMarino | Posted in Green Products and Materials on

I am very concerned about using PEX tubing for the water supply in my home.

I was told that this plastic was BPA-free but when I did some reading I found out that there has been some reports of MTBE’s and some VOCs leeching from this plastic. I also read that this product is not being used in California at this time. I am concerned especially for drinking water.I plan on filtering my water but I would rather not use a product with this concern.

I also have heard of issues of contamination and manufacturing defects in copper tubing manufactured in China. Is an alternative to these products? My plumber is pushing the PEX.

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  1. a non mouse | | #1

    If you have city supplied water, pex will be the least of your concerns. Much safer than where living things drink from. Watch the national geographic channel for a season while keeping my post in mind and you will fall in love with the positives of indoor plumbing and maybe even pex.

  2. GBA Editor
    Martin Holladay | | #2

    Anyone concerned about PEX can use copper tubing and lead-free solder.

    Copper has its own problems and critics, but has a long history of successful and safe use, especially if lead-containing solder is avoided.

    Good luck avoiding plastic, however. It's harder and harder to buy milk in glass bottles, and a high percentage of food items come in contact with plastic routinely. It's an interesting goal, but there isn't much data supporting the idea that PEX is dangerous.

  3. J Chesnut | | #3

    If your question was about the physics and chemistry of moisture and thermal concerns of a proposed wall assembly you would receive a wealth of information backed by good scientific reasoning and field experimentation. The effects of the many varieties of plastics is not a subject that GBA can offer much insight.
    I think it is an important topic but haven't found a source for information or discourse I feel confident in. BPA seems better understood than many other aspects of plastics in that it does enter a body by leaching into water.
    I recently worked on a house for a physician where we had these discussions. The physician decided to take his chances with the copper supply lines instead of pex, accepting the premium in cost.

  4. Steve El | | #4

    I don't like PEX because I try to avoid the philosophic definition of "safe" that was applied to PEX. I do agree the evidence is slim to none (so far) about any problems. I'd just like to point out that at one time there wasn't much evidence that lead paint is hazardous, or radon, or asbestos, or radium that used to be used in glow in the dark clocks and toys. Same goes for a long list of other things. The problem is one of philosophy and economic expediency. It is impossible to conclusively prove a negative (this will NOT harm you) so we test a bit and some people think that bit is enough to turn new products loose on the population.... and some of those products end up causing problems that were not noticed during the bit of testing. I have no reason to think PEX is hazardous. On the other hand, I have no reason to think it is not either. The experiment (purchase by end users) is only in its earliest stages. One can say the same about a long list of stuff, a lot of which is part of my daily life. Compromise happens. PEX is one of the things that has grabbed a slice of my attention, so I just wanted to say that for these reasons, I share your skepticism .

  5. Nelson Labbe | | #5

    Maybe a compromise would be to use pex everywhere except for the cold water line to the kitchen (and maybe refrigerator) where most of the drinking water is dispensed. Use copper lines for cold water to the kitchen.

  6. Riversong | | #6


    J Chestnut is incorrect that GBA is not a place to get reliable advice on such a question, as I've twice answered this question on these pages. And Steve El is incorrect to suggest that there is little evidence or the the choice is "philosophical".

    I've taught plumbing at a school for sustainable building and what follows is my summary of the evidence and my current advice:

    As with most building materials today, it's not easy to determine the relative merits of copper and PEX for domestic water supply. There are significant benefits and liabilities, including deleterious health impacts of both. The following is a summary of the issues. My best advice at this point is to use copper for chlorinated water supplies and PEX for private wells, particularly with acidic water, or with ionic water softeners.

    Copper is a naturally-occurring mineral with associated mining impacts, but it's easily recyclable (and often contains a high recycled content), while cross-linked polyethylene is not.

    Copper domestic water piping must be soldered with "lead-free" solder (no more than 0.2% lead) and fittings (except in CA and VT under new rules) can contain up to 8% lead. Soldering flux is also toxic as well as corrosive to the copper. For this reason and because of galvanic and chemical reactions, copper is vulnerable to corrosion and pin-hole leaks. It is highly vulnerable to frost-breakage. Over time, copper pipes build up a layer of mineral deposits from hard water which constricts water flow and, along with internal burrs and irregularities, creates turbulence and noise. Water turbulence in pipes, often exacerbated by too-small diameter piping, causes increased dissolution of heavy metals such as lead and copper, particularly when water pH is less than 6.5 (acidic, as most water is today). Noise and water-hammer is exacerbated by rigid tubing, angular direction changes and high velocities due to narrow pipe.

    Not only is dissolved lead a problem in domestic water systems, though largely mitigated since the lead ban in 1998, but dissolved copper has become increasingly recognized as a threat to both human health and the environment, limited by the EPA to 1.3 parts per million in domestic water supplies.

    Copper dissolution occurs in new piping, and in piping carrying acidic water, soft water (low dissolved solids), or water with high dissolved oxygen. It is recommended that water sitting in copper supply pipes for more than 6 hours be flushed for 30 to 60 seconds before using for drinking or cooking, that hot water (more dissolved metal) never be used for drinking, cooking or (especially) baby formula.

    Cross-linked polyethylene (PEX) piping, on the other hand, is flexible, smoother, does not scale or corrode, is resistant to acids, and is relatively resistant to frost-breakage. Because it comes in long spools, it has far fewer fittings (usually just one at each end) to leak or cause turbulence, and requires no solder or torch fuels. Because it is far simpler to install, it can typically be done less expensively, even with the now-common "home run" system in which each hot and cold fixture gets supplied by a separate pipe, allowing the use of smaller-diameter tubing, eliminating the pressure-drop common in most homes and allowing a centrally-located "switch panel" to isolate each fixture.

    PEX has been used in Europe since the 60's and in the US since the 80's. It's made from a petrochemical plastic and, while it has 46% more embodied energy per pound than copper, because it is so much less dense (lighter) it has 85% less embodied energy per unit volume.

    Copper smelting and production also creates environmental emissions which cause both human toxicity and environmental impacts. PEX was unanimously approved in 2009, after an extensive Environmental Impact Study, by the plastic-phobic state of California for all water supply systems, concluding that it would be "an environmentally superior action with respect to public health and hazards, water quality and air quality." It is accepted by all North American plumbing codes. However, a lawsuit filed by a coalition, including environmental, consumer, public health and labor organizations successfully overturned the approval in January of 2010.

    Copper ingestion is now associated with flu-like symptoms, kidney damage, Wilson's disease, learning deficiencies in adolescents, and Alzheimer's disease. It is not known whether it is carcinogenic.

    The potential environmental, health and economic risks of PEX claimed in the lawsuit include:

    Contamination of drinking water: methyl tertiary-butyl ether (MTBE) and tert-Butyl alcohol can leach from PEX in amounts that exceed taste, odor and health guidelines set by the State of California for drinking water. PEX can leach ethyl tertiary butyl ether (ETBE), a chemical in the same family as MTBE, which could contribute to taste and odor impacts, and could potentially lead to adverse health effects. PEX pipe is susceptible to permeation by outside contaminants such as pesticides, oil, gasoline, benzene and termiticides. PEX displayed the strongest biofilm formation and the strongest initial promotion of the growth of Legionella bacteria.

    California’s January 2009 approval of PEX relies upon the less-protective PEX chlorine resistance standard ASTM F2023, instead of the much superior NSF P171 standard. ASTM F2023 only assures an adjusted lifetime of 25 years, while the NSF P171 standard assures a 40 year adjusted lifetime.

    Even short term exposure to sunlight can dramatically reduce the resistance of PEX to chlorine and result in premature rupture of the pipe. Studies show just a one-week exposure to sunlight may reduce the chlorine resistance lifetime of some PEX pipes by half; with a two week exposure completely depleting PEX of any chlorine resistance.

    Lack of Recyclability: Because it is a thermoset plastic, PEX cannot be melted down and reused.

    Toxic Smoke: PEX produces toxic smoke when burned in building fires.

  7. Steve El | | #7

    If you read my post again Robert, I think you'll find I used "philosophical" to refer to something else.

  8. Riversong | | #8


    I can hardly read more carefully or thoroughly. I am an skilled editor and consider every word, punctuation mark, syntax, context and meaning.

    So, if you'd like to explain your use of the term better, be my guest. But I believe I read your meaning perfectly.

  9. John Semmelhack | | #9

    There's also polypropylene pipe such as Aquatherm ( I don't have any real information on it...I just know it's out there, and is touted by some as a better option than either PEX or copper.

  10. Steve El | | #10

    "I am an skilled editor"
    That's funny.

    Of the many homes I know among friends and family, only a few have PEX and the rest have copper. I don't know anyone who has suffered from either one. PEX has been around a short time. Copper a long time. I don't know a soul with copper toxicity despite the long use of copper in those homes. We filter our drinking water at the tap. Supposedly the filter is good for copper. That's good enough for us.

    Also, water hammer is an increasing problem from the valves used in various end-of-line gizmos. Hammer arresters can be added at those locations to help absorb the shock.

    "No, I do not have oppositional defiance disorder, and I'll fight anyone who never said so!"

  11. J Chesnut | | #11

    Robert River(t)song,
    I appreciate your detailed post. Can you recommend additional sources of information to follow about the effects of various chemical compositions on biotic life. Are there reputable independent organizations testing materials you could inform us about? Do you think PEX is well understood at this point?
    Chemicals in our environment seems such an extensive and daunting topic that I wish GBA had a regular blogger to push the topic as far as topics such as wall assemblies are pushed.

  12. Steve El | | #12

    I'd love to see that too J. One MAJOR problem is that there is practically zero funding to study how synthetic chemicals interact with each other AFTER they have been 'disposed' of (often by dumping, flushing, pumping, injecting, burning etc) in the wild. The philosophic perspective used by our rule makers in defining "safe" does not usually take this into account.

    "No, I do not have oppositional defiance disorder, and I'll fight anyone who never said so!"

  13. A non mouse | | #13

    PEX is NOT a new product. Like I said, drink from a stream and tell me how you like beaver fever and the rest of the nice not so trace goodie that may take over you health.

    PEX is great stuff. Riversong's post is the the cat's behind.
    a non mouse

    What is making kids big and girls go into puberty sooner? Overeating... OVERFEEDING! Americans eat enough for a family of four each and every one of us. So it is said.....

  14. Riversong | | #14

    Do you think PEX is well understood at this point?

    Not at all. But neither would we have guessed that copper can be toxic, and increasingly so as our rainwater gets more acidic. And "lead-free" solder and fixtures still contain lead. We still use mercury (a very potent neurotoxin) in dental work, and its replacement is various forms of epoxy. We put the industrial waste product, flouride, in our drinking water and poison whole populations with chlorine.

    So many instances of unintended consequences. We build everywhere we can put a house, drill a well and then don't like the mineral content of the groundwater. So we install expensive water softening systems to demineralize out drinking water. This makes water "hungry" - meaning that it dissolves any metals it contacts, including copper and lead. If we don't soften the water, however, the copper pipes build up mineral deposits on the interior, increasing turbulence and pitting the pipes at angular changes where the copper is scrubbed from the accelerating water. If the water has a high iron content, it will grow iron-feeding bacteria that leave a rust-colored sludge.

    Polyethylene is likely the cleanest of all the common plastics (it produces no smoke when it burns), and is commonly used for FDA-approved food containers. PEX is certified by both NSF and ANSI as suitable for potable water. Of the three types of PEX (a, b and c), PEX-C is the safest.

    I get my drinking water from a stream. I run it through a paper and a charcoal filter and then a third Brita filter for drinking. It's good, wonderful-tasting water. But, since I don't have indoor plumbing, I don't have to worry about my water sitting in metal or plastic pipes. My food-grade polyethylene water barrel has not grown any mold slime in five years of constant use.

    But it's also true that bacteria will culture better on plastic than on natural materials like wood. Wooden cutting boards are far superior to plastic for health reasons.

    We've created a largely artificial world and are reaping the consequences in epidemics of chronic and debilitating diseases, as well as increasing incidents of multiple chemical sensitivity. We are overly concerened with cleanliness and don't get exposed to the earth around us which offers natural immunities.

    The simple truth is that we can no longer escape the consequences of our own ignorance. For all our "progress", we are the most ignorant human population in the evolution of our planet.

    My uncle, who (like everyone in the generation before me) died of cancer, was a lifelong practicing physician and professor of medicine, with an MD and PhD from Harvard. He was on President Kennedy's medical advisory staff and attending almost every medical conference in the world, being one of the few Americans allowed behind the Iron Curtain for academic exchange. His wife was a physician and all three of his children went into some field of medicine.

    But, as he was dying of cancer, having given up on all the most cutting-edge medical "miracles", and having learned macrobiotic diet and meditation so he could at least die well, the last thing he said to me - a man who was one of the world's most dedicated medical doctors - was "We just have no idea what we're doing."

    And that's the simple and awful truth.

  15. oleBob | | #15

    pssst. There are millions of folks getting water from copper and /or pex. You folks are so intellectual superior, I wonder why your ancestors falied to extinguish us mere mortals.

  16. Riversong | | #16

    I wonder why your ancestors falied to extinguish us mere mortals.

    No need. You're doing just fine in that direction all on your own.

  17. Lucas Durand | | #17

    pssst. There are millions of folks getting water from copper and /or pex.

    pssst. There are also millions of people eating McD's or some equally foul fare for every meal of the day.
    Just because we take something for granted doesn't mean we understand it fully.

  18. Riversong | | #18

    Don't bother Lucas, he's just another troll.

    I think this disease is spreading faster than the cholera in Haiti.

  19. Riversong | | #19

    Or it could be that he's got too much copper and MBTE in his brain.

  20. Doug | | #20

    Response to J. Chesnut, "Chemicals in our environment seems such an extensive and daunting topic that I wish GBA had a regular blogger to push the topic as far as topics such as wall assemblies are pushed."

    Agreed, the lack of information and knowledge are disconcerting.
    GBA and Building Green do as good a job with this as anywhere on the web, possible exception of their new partner, the Pharos Project of the Healthy Building Network.
    Head over to for the announcement.

    Pharos is a spectacular program, albeit in its infancy so not nearly as extensive as it will need to be for daily use.
    They have a live, constantly updated, and very large list of chemicals that have been listed to have some level of toxicity, including copies or links to the governmental or academic organization's documentation on the chemical. So anything tagged on any warning list by the EU, US, or numbers of other organizations is on the Pharos list, accessible to Pharos users for further research.
    The Pharos site also has a list of construction materials including their ingredients, and allows comparisons between products in a category like insulation. They have several categories pretty well filled out and hopefully will continue to add more.

    Still, the likelihood of health effects will still be something of a guess, and will change due to any number of factors, so it's still a bit of a crapshoot. No harm learning more about what's in stuff and how toxic it's thought to be though.

  21. John Reimers | | #21

    If the water service from the meter to the house is in PVC pipe, as well as the water main in many places, how is the importance of the internal house piping affected? Whether PEX or copper is used seems somewhat mute if the main service is already carried in one of the worst types of pipe.


  22. Riversong | | #22


    You're quite right. In rural America, we get our water from private wells or from springs, so the choice of indoor plumbing is important.

    But the bigger issues of concern than the type of municipal supply pipe are the chlorine and flouride (an industrial waste product) that are poisoning people daily (and how they interact with plastic piping).

  23. Anonymous | | #23

    The sky is falling...


    is the new buzzkill

    Give me a BREAK!!

    LIFE LEADS TO... guess what nervous Nelly's... YUP... DEATH. (PERIOD) (END OF STORY)

    Please enjoy the ride you get one shot that we normal humans know of.

    live, love, dance, laugh, cry and worry not about your friggin water pipes!

    Yaa ain't gonna get out of this place...


    and... with all the rotten crap known to the 29th century, grandma said she lived too long... 99 was about a decade more than she desired... What is with this God we all talk to?

    ADD? Not the best listener for sure.

  24. Anonymous | | #24

    typo "20th century"

  25. Riversong | | #25

    Actually, Chicken Little was right:

    The Sky Is Falling
    The odds that a potentially devastating space rock will hit Earth this century may be as high as one in 10.

  26. Anonymous | | #26

    Well crap, I no more know which is the best option than when I started doing my research. Sigh.

  27. anonymous | | #27

    Look prior poster. No pipe made today will kill most of us before something else takes you off this planet.

    Find a new worry. Toss a coin, and plumb. If you can't do such then don't use any pipes or plumbing.

    Have you noticed any of your neighbors dropping like flys after living in a home with indoor plumbing?

    The stuff we waste time worrying about is nuts.

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