Permies opinions on the purity of potable PEX?

I'm having some plumbing issues and thinking about swapping out my copper pipes with PEX. Is there any permie consensus on PEX vs copper?

I generally go for the more traditional technologies, assuming that we don't know what we don't know about the longevity of or potential toxins the newer products - but I am seeing significant deterioration in my house's copper lines which are only 28 years old. My well water must be acidic. Where ever we use a lot of hot water - especially the shower, it stains blue and we must clean with vinegar every 2-3 weeks. I replaced the anode rod in our 10 year-old electric hot water heater to see if that would fix it, and it did not. The old anode rod was completely deteriorated (as in gone) and I assume it deposited anode rod debris through the pipes which become chunky bits of turbidity and catalysts for further reaction/deterioration of the copper. Two weeks ago I found my first pinhole leak near the water heater.

My basement is finished but I currently have the ceiling down because over the last year I had a flooded laundry room, and then a busted drain, and then a clogged drain. Fixing all of that wrecked the place, but I do now have access to 80% of the pipes. With my water heater at end of life and more pinhole leaks likely to develop I think it would make sense to handle some of this plumbing work before putting up a ceiling.

Any opinions on copper vs. PEX with respect to purity and cost? I understand the PEX tools can be a bit pricey but it's easy to work with when you get going. I can solder but I'm seeing lots of Ts and elbows down there in tight spots...

Thanks a bunch.

I have a permie opinion on PEX! I advise against it, as it's another petroleum based plastic, and chemicals in that plastic can leach into the water in those pipes. That's partly why PEX is banned in california. The following quote comes from this article: https://www.ewg.org/enviroblog/2017/11/amid-pipe-wars-researchers-wary-plastic-pipes-leaching-chemicals#.Ww2-NC-ZNTY

In one of the first U.S. studies to look at numerous brands of PEX pipes and their effects on water quality, Whelton's research team tested six brands produced by different manufacturing methods. They found that each type caused odors exceeding the Environmental Protection Agency's guidelines, and leached chemicals such as toluene, which is neurotoxic, and MTBE, a carcinogen that's been banned as a gasoline additive, but is a byproduct produced during PEX pipe manufacture.

There's also more information here: https://www.purdue.edu/newsroom/releases/2014/Q4/drinking-water-odors,-chemicals-above-health-standards-caused-by-green-building-plumbing.html

I think pex is nasty stuff. Copper on the other hand I think is great. It's easy to sweat together, lasts a long time, doesn't corrode, and the properties of copper helps keep undesirable bacteria from thriving in pipes.

Forgot to mention, if you do choose to use copper, I suggest the Type L copper instead of the cheaper Type M. The type L has a much thicker wall.

The big win/dealbreaker with PEX is that it is resistant to freezing. If you're building a RV/van or uninsulated cabin, it's a very compelling alternative to copper pipes. Having an uninsulated bathhouse that was piped with copper and compression fittings that I have to repair every year, I often feel the temptation of repiping with PEX. But like all plastics, there's a lot of wishy-washy-weird-gicky-theories associated with it. As James mentioned, PEX was outlawed in California until 2009. This was based on fear from a study about off-gassing that was never able to be reproduced. California's compromise was to allow PEX (it is legal now), but require two weeks of off-gassing and flushing before the system can be used for potable water. That's enough evidence to give me pause.

There's still no "proof" (accepted peer-reviewed science) the off-gassing affects water quality or even that it happens. But with petroleum products, it seems like we often find the bad effects a few decades later when someone is able to squeeze the truth out of the industry.

That being said, I would definitely think about looking into altering the water's chemistry coming into your home. Repiping your house is going to be very expensive, very inconvenient, and very frustrating no matter what you repipe it with. Altering the water's chemistry is the only real solution to preventing corrosion.

Thanks James and Kevin - thanks! I never would have considered PEX but my copper pipes are corroding so my family is ingesting some kind of inorganic copper salt gick which may or may not be better than the organic PEX gick. Changing the water heater anode didn't fix the chemistry - I understand that some anodes can have more or less aluminum or magnesium - I just ordered from Kenmore/Sears by part number and maybe I ended up getting the wrong type. I suppose a special filter right after the well pump could do something. I get the blue water stains only where we run hot water, so one thing I considered was running red PEX for the hot water lines and keeping the cold lines copper (since we only drink from the cold lines). However - my pin hole leak is in a cold water line so there are likely several things going on.

As for cost - I'll have to do some plumbing replacement anyway - I have the one pin hole leak and I see green corrosion spots at many places on the outside of the pipes - particularly around joints. My next ceiling will give me full access, so I for now I can just replace some of the easy runs and most corroded joints and deal with other problems that arise later. The incremental cost is really the difference between copper/PEX joints and runs, the PEX tools and of course time (I'm assuming the PEX goes together faster, which may not be the case).

Anyway - still looking for things to consider. I think a water test is definitely in order and I'll do that before buying the water heater and PEX or copper.

BTW, this is the video that led me to change the anode rod 2 years ago. Interesting to see what is happening inside your copper pipes.

I have PEX in my Bay Area home. Although I don't know about the long time effects, nobody really does, do they,  I went with it because the chloromines  in our water are supposed to be hard on copper piping. This replaced galvanized at our house.

Do be aware, that PEX piping doesn't provide a ground for your electrical.

The papers linked above seemed to indicate that clorine in the water had a greater effect on smell/levels, but honestly if it's releasing chemicals that you are either consuming or washing in, I wouldn't gamble the health of the family over it. I was thinking PEX would be a convenient option for a homestead, but not if all the brands are leeching into the water. I have a Berkey filter but I'm doubting it would clean up the leeched compounds.

I was surprised to see that the articles above stated that the cost of a copper plumbing job could be 5x higher than a PEX job. Labor related to the ease of PEX installation must be a driving factor there. When looking just at materials based on local Home Despot prices I see the following:

200’ of Type-L copper (100’ of each 0.5” and 0.75”) at the HD would cost $374.90 or $299.90 at the bulk/contractor price available for these quantities. This compares to $77.21 for 200’ of Potable PEX.

However, 40 copper elbows and tees (10 of each size/type) would cost $29.89 where as the brass PEX fittings and 150 required crimp rings would cost $86.15. There are cheaper plastic fittings for PEX that I would not want to use.

Totals for the configurations above:
Type-L copper: $329.79
Type-M copper: $259.19
PEX: $163.36

I got the same PEX order down to $138.06 (shipping included) from an online PEX specialty company. The difference was mainly driven by the brass fittings which were 30% cheaper online versus the big box stores. The PEX prices were nearly identical.

Of course I would need the PEX tool and several of the more expensive PEX to copper fittings for places where I’m tying back copper pipes I don’t remove.

From a material perspective I think 50% cost savings realistic.

Toxicity and longevity is another issue.

Mark Tudor wrote:The papers linked above seemed to indicate that clorine in the water had a greater effect on smell/levels, but honestly if it's releasing chemicals that you are either consuming or washing in, I wouldn't gamble the health of the family over it. I was thinking PEX would be a convenient option for a homestead, but not if all the brands are leeching into the water. I have a Berkey filter but I'm doubting it would clean up the leeched compounds.

The leached chemicals only happened when exposed to chlorine and even then only for the first couple months.  The issues with odor are purely aesthetic and not health issues.

THis doesn't mean that PEX is perfectly safe, but then I doubt that anything in a  home (man-made or otherwise) is "perfectly" safe.  Walking around in the dirt barefoot is potentially more hazardous than PEX.

I personally think Pex is almost better than sex, but then again, I hate plumbing.

The real advantage of Pex to me is how fast it can be installed. It is the equivalent of roughing in electrical connections, just drill a hole and run the Pex through it. A few connections here and there and I am done. I could never do that with copper. For me, my time is worth something, and reducing it doing something I dislike is a huge benefit.


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By the way: as a general rule, the difference in copper between M and L is thickness, but the thinner copper is typically used in heating systems and not in domestic water because the thiness allows better heat disapation, so it is kind of backwards from what people think.

Haha. I do lean Travis's way on this. Value my time highly. I think toxicity is everywhere and unavoidable so for me it really about managing incremental exposure. I like to brush my teeth, hard, with a little stick full of different plastics and I'm too lazy to change that. That said, I have great respect for you HUSP people and those tinkering with their environments to limit their toxic exposures and sharing their experiences with the rest of us - coming up with new ways to make that easier for more indifferent people like myself.

My plastic tolerances have changed over the years and I reserve the right to change my mind in the future. Right now I'm fine collecting tree sap in an HDPE bucket, but when I see those complex aquaponics systems full of plastic tanks and pipes I think it looks a little icky and it's not for me.

Similarly, I'm being convinced that PEX is most likely OK (for me) if I run the water for 30 seconds before drinking it, but when I see these "lifetime" non-metallic (all plastic and foam) water heaters - where a larger volume of 140 degree water is in contact with plastic 24/7 and I think that might go too far (for me, of course).

Copper has a long history as a plumbing solution and the long term disadvantages and effects are known. PEX is not. The press fittings for PEX piping have not been proven over time in domestic settings. They are theoretically good, but life has a habit of interfering with theory...

PEX is supposedly stable and "shouldn't" leach toxic gick into the water. That's the toxic gick they actually test for mind you.

Here is a big cautionary note about PEX. It is extremely sensitive to UV exposure. It hardens and becomes brittle if exposed to sunlight extremely quickly. If it's left outside for as little as 2 weeks, its lifespan can be halved. So connection failure and leaks may happen 10 years down the track simply because it was mishandled somewhere along the distribution chain.

I have PEX in my own house. For hot water systems it's great because the hot water stays hot in the lines, and we don't drink water from the hot tap anyway. Ideally I would have all our cold lines copper because it's a known quantity.

We installed PEX about 18 years ago in our mid-1800’s brick house to replace terribly corroded copper (one 10 ft section had more than ten mends along its length). I have to echo Travis on the time saving aspect. One bathroom in an addition outside the original shell would have required at least 6-7 elbows (times 2) to plumb with copper, along with crawling in the 30 inch crawl space and would have taken me half a day to complete. PEX took me twenty minutes. As the house is seasonal (for now) we drain the pipes in winter and I used quick connects to facilitate that.

In the last ten years I have developed a form of super sensory smell (Hyperosmia), to the point that certain areas of stores (such as air freshener areas if leaks have occurred) I can barely breath. I am unable to detect any odor from PEX. Our water is from a sand point at about 25 foot.

The quick-couplings (one brand is called Shark-Bite) were developed for use on Submarines. They needed a fitting that could instantly be added to a pipe that had broken because a flooded compartment would be detrimental to the Submarine obviously, and all hands on board. What they came up with was quick, allowed use on multiple types of pipes, and held. Considering it literally meant life or death for sailors, I have no issues with its ability to hold.

In my house, I started using pex 12 years ago and all my fittings are quick-couplings. Part of there use is because of the quick amount of time to install them...just press in and go, and part because I am always changing things around. The ability to pop off fittings and reuse them has really been a benefit, so their cost (while higher) is not an issue for me. In 12 years I have never had a fitting leak or come loose. I cannot say that about my boiler that has copper fittings and pipe. I have had two leaks in 12 years, and it operates for half the year, and at 1/3 the pressure compared to my domestic hot water.

I've used the Hep2O plastic system for a couple of projects. As a non plumber it was a piece of cake to do, no leaks, quick, cheap. If all these plastics we have been using for a couple of generations are leaching toxic chemicals into what we consume then how is life expectancy higher than ever? I'm being told don't use plastic cups. straws, bottles etc cos they take 10 billion years to break down then I'm told the pipes that come with a 50 year warranty are going to break down in ten years. Can't both be true.

https://www.wavin.com/en-gb/Catalogue/Potable-Water/Plumbing-Systems/Push-fit-Hep2O
This stuff is easy to find from various sellers on ebay.co.uk

I don't know if this is a PEX or some other type of plastic. I have seen it referred to as "PB" on their website if that means anything in this context?

Its amazing to hear of the issues you have with pipes.

Quick question for Travis and others that are not PEX-averse - I see the sharkbite fittings are around $10-15 each, whereas the same brass elbows and tees that are used with the crimp rings are less than 10% the cost. Do you think it's worth paying up for the sharkbite fittings? I'll need a few to tie into copper pipes that go up through the walls, but in places where I have access it seems that using the simple brass fittings and crimps will save a bundle.

Also - would you be willing to pay twice as much for a plastic lined water heater that is supposed to last 10 times as long?
https://www.rheem.com/products/water_heating/tank/marathon-electric-water-heaters/

Yes, I think they are worth it because they are never wasted. When I change things around, I just pop them off and reuse them, or save them for another project at a later date. I have quite a few now so for most plumbing jobs, I just buy one or two fittings and my project gets done. With Pex's long lengths, most of the time a job is really only a few fittings, unlike copper or plastic pipe that comes in 10 foot lengths. PEX can often make some pretty tight turns too so elbows are not required as much as other types of plumbing.

My house is 100% sharkbite fittings with pex (except for my boiler system which is copper before going into pex radiant tubing at the flow control manifolds.

I see nothing wrong with crimp fittings though. Especially if you know someone that has the crimp fitting tool that you can borrow it from.

Super. Thanks for sharing your experience Travis.

I ended up going all plastic on this project - all plastic water heater with a 100 year guarantee (10-12 years on elements), PEX manifold with a 10 year guarantee and PEX tubing which is supposed to have a 25 year life. The copper pipes started developing leaks around year 20. I have some sharkbite fittings in places but ended up getting the crimp tool because I like right angles and it's cheaper that way. I've replaced about 40% of the pipes and will have it 70% replaced by the end of the year. The remaining 30% of the pipes are behind drywall so I'll wait for a leak to develop before attacking those. It's just a matter of time - the plastic water heater has no anode rod so the pipes are now the only thing left to attack. Check out what 28 years of slightly acidic water can do to the inside of a copper pipe on the hot water side. While everything was torn apart I also added a sand separator and sediment filter. There was quite a bit of sludge in the copper pipes. Water tastes significantly better now. I'm glad I made the switch.

We have PEX in our home. I have to say that performance isn't an issue. Installation is. It is easier and faster. However, PLEASE resist the temptation to skimp on mounting your PEX tubing to something solid. Our PEX is the nosiest stuff in the world. Every toilet flush, every shower, every dishwasher cycle, every washing machine cycle, every sink use of our water causes the PEX to rattle and bump in the walls. I recommend doubling the number of fixing points that code or instructions call for. Any change in pressure (turning on and off of any value in the system) causes our PEX to be very noisy. I'm sure a better job of affixing the tubes to studs and joists would have solved this, but I wasn't the builder and someone somewhere along the line didn't do a good enough job of securing all the tubing.  Word to the wise.

Steve Farmer wrote:I'm being told don't use plastic cups. straws, bottles etc cos they take 10 billion years to break down then I'm told the pipes that come with a 50 year warranty are going to break down in ten years. Can't both be true.

There's quite a bit of difference between a pressurized pipe failing in a way that results in a home flooding and a piece of plastic degrading to the point where you can't tell the difference between it and the surrounding environment.  Mostly what plastic does is break into smaller pieces of plastic - not change chemically.  So, if you think about it for a minute, it seems fairly clear that both statements can actually be true.

I have PEX in my house. It makes plumbing really easy for the non-professional plumber. I saw the comments about toxins. My husband tested the water from both our tap and the spigot next to our well and they had the same results. No toxins other than the Hexachrome issue. So I don't think PEX is a problem for us.

I have used Polypropylene drinking-water grade pipes for cold water. No taste whatsoever. (And freeze tolerant!)
As far as hot water is concerned, I am leaning towards an isolated hot-water circuit (with distilled water inside), that transfers the heat through a heat-exchanger just before the hot water tap. It eliminates corrosion in most of the parts, and the part that does come in contact with fresh water can be made from stainless steel.

As far as copper pipes go … the hot water pipes (40 years old) didn't have much of the wall thickness left when we took them out. And the cold water iron pipes were filled with deposits …