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Community and Q&A

Water Testing After Pex Repipe

JohnZ99 | Posted in Green Products and Materials on

I live in South Orange County, California, a repiping companies paradise. A massive amount of newer homes are being forced to repipe due to copper failing and slab leaks. The pinhole leaks begin developing between 8 to 15 years after the home is built and sometimes sooner. The theory according to most is that the builders went cheap and installed copper M in the homes, while the water company uses cholormine which the Copper M can’t handle. Most repiping companies will recommend PEX A, but also market USA made Copper L for the repipe. Some of the repipe companies that have installed copper L said they have seen pinhole leaks develop 12 years after it being installed, even with the USA Copper L.

I’m inclined to use PEX on my repipe, but a couple neighbors who installed the PEX A still have a chemical smell in the water 30 to 90 days after installed. One neighbor who installed PEX over a year ago said the smell went away on high use areas, but still a year after can smell the water in sinks not used frequently.

I’ve seen some of the studies from Dr. Andrew Whelton about various pex brands and some of the chemicals found in the water including ETBE and MTBE. Most of the studies were short term focused 30 days or less, so its really hard to determine if PEX leaches chemicals in the water after the pipes have significant use over a long term.

It seems like the California Environmental Study on PEX was also concerned about short term impact of PEX since it makes all new installations flush twice to prevent construction workers from ingesting MTBE on a daily basis as they move from site to site. But does this mean PEX chemical leaching is only a short term impact on the water supply?

Has anyone installed PEX in their house and had a detailed lab water test analysis a year or two after the fact? I love to hear the results.


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  1. GBA Editor
    Martin Holladay | | #1

    I don't think that there is a meaningful test to determine the answer to your question, but I'm eager to hear if any GBA readers have useful responses.

    The "PEX versus copper" debate has raged on GBA for at least 8 years. If you want to read more on the topic, here are some links:

    How Safe is PEX Tubing?

    PEX tubing

    What is the greenest and best material to use for indoor plumbing?

    PEX vs Copper

    Green Plumbing Systems Save Water and Energy

    Water supply - PEX?

    Lingering Questions About PEX

    PEX A vs. PEX B

  2. JohnZ99 | | #2

    Hi Martin,

    Thanks for your response and the articles. In my research on this topic, I've definitely seen most of those articles and I'm looking forward to reading the others. The "Lingering Questions About PEX" article is a great one, and I can't believe with all the PEX being installed in the USA there is not more long-term research being done on this topic.

    Before I repipe in PEX, I'm thinking of asking one of my neighbors that has installed PEX to allow me to test their water with a lab test like this one:

    It tests for most of the VOCs such as MTBE and Toluene which seem to be noted contaminants from PEX manufacturing.

    I'm just not sure what to do.

    Do I repipe in USA Copper L and risk more pinhole leaks 10 to 12 years down the road or repipe in PEX and risk it is not safe for my health.

    I know NSF claims PEX is safe in its standard However, I think Dr. Andrew Whelton studies cast some doubt about this standard. And just my basic common sense tells me that if my neighbors water smells like chemicals 3 months after PEX installed, something is definitely not normal about the PEX.

    I'd love to hear what GBA readers have to say on this topic as well.

  3. this_page_left_blank | | #3

    As far as I can tell, the difference between M and L copper is only thickness. It's the same material. So it's unclear how a chemical incompatibility with type M would be any different for type L. Granted, the thicker wall will prolong its life, but if the issue is chemical corrosion, its ultimate fate is the same. I would not feel that great installing pipe that is destined to fail in 16-30 years.

  4. GBA Editor
    Martin Holladay | | #4

    Yes, L is thicker than M.

    And if you want thicker still, order type K copper.

  5. JC72 | | #5

    There are different types of PEX. That matters !!! PEX-B is apparently resistant at leaching chemicals which impart an odor.

  6. Yamayagi1 | | #6

    I just finished a new home in Massachusetts that is all (Uponor) PEX A for domestic water and (NFPA13D) fire sprinkler system. I had read about PEX A taste concerns before building, but have not been able to detect any smells at all. Domestic supply is city water of marginal quality, filtered by a sequence of 10" sediment filter followed by a 20" charcoal filter. I am at the end of the water line. I would do it again the same way if I were to do it again. Only mistake was to go 1/2" PEX from the hot water manifold to the sinks instead of specifiying 3/8" for even faster hot water response.

  7. JohnZ99 | | #7

    @JameKreyling, Thank you for your response. It's definitely encouraging. I am glad there is no smell with your new install. With the exact same PEX you noted there is definitely a noticeable chemical smell in the water here in Southern California. I suppose this smell is the same smell noted in the short-term studies by Dr. Andrew Whelton. The smell is more pronounced in sinks that are used less frequently. It becomes less pronounced after the water runs for a bit. Refrigerator carbon filters seem to remove the smell, but I have to wonder if the filter is actually removing the VOCs from the water. After smelling the water I am very surprised that PEX is becoming a standard piping material. Hopefully for the safety of everyone some long-term studies will come out indicating that VOCs from pex are just a short-term side effect of the manufacturing of the pipe and with long-term use the VOCs disappear.

  8. Expert Member


    The smell must be a reaction between pex and specific characteristics of the water in some regions. Pex is the default material for all new houses here in BC and I've been installing it for 20 years without hearing of or experiencing odd tastes or odors.

    The majority of the construction around here is on private, rather than municipal, water sources, and each has to have a chemical analysis before the house can be occupied. I don't know what the specific VOCs that occur in the new Pex installations you experienced are, but I'm surprised they don't show up in these tests. Perhaps they are looking for different things?

    None of this is meant to dismiss or denigrate your concerns. I'm just pointing out it isn't a universal problem with Pex.

  9. JohnZ99 | | #9

    Hi Malcolm, Thanks for the response. That is good to hear about your installs with PEX. I suspect you are correct it is probably something interacting with the PEX from the municipal water supply. Most repipe companies theory on why copper is failing in this area is a result of chloramine added to the water by the city. I'm just hope the smell in the water after PEX installs is not being created by something like was noted here:

  10. Expert Member
    MALCOLM TAYLOR | | #10

    The levels of residual chlorine in municipal water supplies do vary widely. It could be that. Most of the water systems I'm familiar with currently rely on 1 to 5 micron filters and UV as their primary treatment, adding chlorine to the supply mainly to keep the storage tanks and pipes clean, so the amount of chlorine used had diminished a lot in the last decade or so. There are a number of other side effects of over-reliance on chlorination that aren't too great. One is they create THM's which are hazardous. The publications I get on managing municipal supplies suggest they are working to phase-out chlorination entirely.

    I manage several small water systems so know a bit about this stuff, but unfortunately not enough to be of much use to you. I simply don't know if the analysis we get done here on pex installations is looking for the right things.

    Good luck!

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