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What are the advantages/disadvantages of Pex tubing? How does it compare to copper?

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  • See similar question: diy.stackexchange.com/questions/1331/…
    – gregmac
    Aug 26, 2010 at 20:17
  • PEX may stretch and return to its original size, but NO material can continually do that. Metal will get brittle, not sure what happens with PEX, but every piece of plastic I've ever seen loses elasticity and gets extremely brittle over time.
    – John John
    Dec 2, 2016 at 13:45

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From Pex Information:

  • Flexible PEX tube is manufactured by extrusion, and shipped and stored on spools, where rigid plastic or metal piping must be cut to some practical length for shipping and storage. This leads to several advantages, including lower shipping and handling costs due to decreased weight and improved storage options.
  • PEX plumbing installations require fewer fittings than rigid piping. The flexible tubing can turn 90 degree corners without the need for elbow fittings, and PEX tubing unrolled from spools can be installed in long runs without the need for coupling fittings.
  • Attaching PEX tube to fittings does not require soldering, and so eliminates the health hazards involved with lead-based solder and acid fluxes; PEX is also safer to install since a torch is not needed to make connections..
  • PEX resists the scale build-up common with copper pipe, and does not pit or corrode when exposed to acidic water.
  • PEX is much more resistant to freeze-breakage than copper or rigid plastic pipe.
  • PEX tubing does not transfer heat as readily as copper, and so conserves energy.
  • Water flows more quietly through PEX tube, and the characteristic "water hammer" noise of copper pipe systems is virtually eliminated.
  • PEX plumbing installations cost less because:
    • PEX is less expensive than copper pipe.
    • Less time is spent running pipe and installing fittings than with rigid pipe systems.
    • Installing fewer fittings reduces the chances for expensive callbacks.

If you are only going to be doing a little bit of work, check with your local rental stores, you may be able to rent the tool for a decent price.

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    The spool isn't always an advantage -- it means it's going to try to curl back up on you as you're running it. I've seen professionals who use the sticks of PEX, which defeats the advantage of fewer connections, but they said it goes up quicker than gluing PVC, and more forgiving if they need to bend it to route around an obstruction.
    – Joe
    Jul 22, 2010 at 15:50
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    I've used both spooled and stick PEX, and can say without a doubt that the spool isn't worth the hassle, and it ends up looking like junk -- even the shortest lengths will have a visible curve when you're done.
    – Mike Powell
    Jul 26, 2010 at 5:03
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    While soldering may still may be the most common method of joining copper pipe it should be noted that alternates such as ProPress and SharkBite exist that do not require solder and flux.
    – pdd
    Jan 3, 2013 at 19:40
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    The spool is not bad if you plan a bit ahead and lay out your run in the sun for a hour ahead of time. Helps take the curl out. I also like the red and blue option on the tube, easy to ID hot/cold in future. Been used a lot in mobiles for years. Can be easier to fish through old walls that are not open.
    – spicetraders
    Oct 6, 2016 at 16:45
  • @pdd Aren't copper press-fitting like the ones you mentioned intended for repair work vs. whole-house installs?
    – Josh M.
    Oct 18, 2017 at 19:15
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Another advantage to PEX if you're doing a from-scratch installation is that it's typically installed using a manifold at the water source with a run to each faucet. That approach significantly reduces pressure loss at one faucet when another faucet on the same branch is turned on, as often happens with copper plumbing.

You could do the same thing with copper, of course, but it would be prohibitively expensive in time and materials.

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  • This is a great point. We have PEX with a manifold in our new house. I can turn on practically every faucet with no loss of pressure.
    – aphoria
    Jul 22, 2010 at 16:51
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A huge disadvantage with PEX is that it is semi-transparent. If your water supply has nutrients in it and the PEX is installed so that light will get to it, you will find that algae (green), bacteria (black, orange or yellow) will grow inside it. It sloughs off in long, stringy goop similar to the biofilm that grows in diesel tanks that haven't been treated to prevent bacteria growth. Keep it well hidden in walls and away from crawlspace vents where sunlight can penetrate.

diy even has a question submitted on the subject

Keep squirrels away from it, they find it delectable.

Also another advantage listed is that there's no lead. That's true insofar as you stay away from the type that requires brass fittings.

Otherwise, you have a highly flexible, smooth bore water supply system that will allow for using smaller tubing, which can speed up hot water temperature delivery. It's cheap enough that you can do end-run (star) delivery to a central control manifold, typically each run will only have two joints, one at the manifold and one at the the coupling to the shutoff valve. You also don't have a problem with meth addicted copper thieves coming and stripping your house plumbing out if you leave it unattended (summer cottages, another reason iron ain't so bad).

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There is one huge advantage I see just from reading these posts.

No More Copper Thieves!

I live in New Orleans and had to have my whole system redone because it was cut and stolen.

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  • That's a sad, but very good point. ;)
    – DA01
    Sep 1, 2011 at 17:17
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    I've heard of people who replaced copper with PEX, where the price for the PEX came out to about the same amount that they got out of the copper.
    – Brad Gilbert
    Oct 28, 2011 at 5:45
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    Yeah, but after some of these glowing answers, thieves will be craving PEX pipe.
    – Kaz
    Mar 29, 2013 at 5:33
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There are many examples of building products that claimed to be "the wave of the future" and turned out to be utter failures, sometimes dangerous. (polybutylene plumbing, aluminum wiring, and asbestos building products to name a few.) Despite the manufacturer's glowing claims, the actual long-term characteristics and behavior of PEX tubing cannot yet be known.

One of copper's distinct advantages is its long history of solid performance and desirability.

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With pex pipe you just need shark bite fittings . Don't require special tools for installation.. shark bite fittings are considerable more expensive than others but you can fix a leak without ever turning the water off if you like

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    I'm a huge fan of SharkBites--at least for DIY repairs. I don't know if I'd do a whole house in it (due to the cost) but they are absolutely the best thing for small projects--as well as connecting PEX to existing copper.
    – DA01
    Jan 14, 2014 at 5:49
  • I was wondering why DiY'ers needed expensive tools.
    – Mazura
    Sep 26, 2014 at 3:50
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I know PEX is cheaper (specially considering the rising price of copper), easier to run and less noisy than copper but you have to buy a special crimping tool for the fittings (don't know how expensive the tool is). My only fear would be long term effects depending on water type. For instance I have very hard water (very high calcium content; I should NEVER have to worry about osteoporosis) and I wonder what will happen 10, 15, 20 years down the road to the PEX pipe based on the minerals in the water.

I'm also not sure if there are any long term health effects from having water run over PVC. Not sure what kind of chemicals leach into the water over time. I'm 99.99% sure it's safe though.

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    The tools are often quite expensive. I looked into purchasing a tool to work with PEX that a contractor installed in my house (I've forgotten which brand). It was over $200 for something that was really a simple crimping tool.
    – rsgoheen
    Jul 22, 2010 at 14:31
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    Note that PEX and PVC are two different things.
    – DA01
    Sep 1, 2011 at 17:17
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    Two years later - PEX crimping tools can be had for about $80 and that includes with multiple crimp heads.
    – The Evil Greebo
    Jan 3, 2013 at 19:34
  • You can get some very basic crimp tools for around $20, but they require vise-grip pliers to close, and would get pretty annoying if doing more than a handful of crimps.
    – joshdoe
    Mar 7, 2013 at 17:13
  • And with copper you need to buy and operate a torch, and solder, etc. The PEX tools are $8 for the cutter, around $100 for the crimper.
    – Josh M.
    Oct 18, 2017 at 19:19
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Get a pinch clamp tool, like this one, and a pipe cutter. Those are the tools you'll need. One tool works for all size pinch clamps.

  • Copper has antimicrobial properties.
  • Copper will oxidate and leak under certain water and electrical conditions.
  • Copper that is not completely dry and clean cannot be soldered.
  • Pex can be fixed underwater and covered in poo.
  • Out of the 1000s of pinchclamps I've installed, not one has leaked.
  • Pex fittings can be easily undone and reused, just heat the pipe slightly.
  • Out of the 10 sharkbite fittings I've installed, one leaked.

If you have to use a slip on style fitting, smear the outside of the pipe with plumbers grease.

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From comparing chart PEX vs Copper

PEX tubing has much much better freeze burst resistance properties than copper. Its very important especially for people who lives in cold climate areas.

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There is a notable potential downside with PEX (and I'm saying this as someone who's chosen it for his own house).

PEX has the lowest strength of the three most common materials. If I recall my numbers correctly, copper will burst at something over 5,000 PSI. CPVC at around 3,000, and PEX at around 1,200.

Of course, if you get 1,200 PSI in your system to begin with, you've got bigger problems. But still...

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    Since you'll often have at least one valve that fails around 100psi (running toilet or dripping sink), and the TPR valve on the hot water tank will give out at 150psi, it would take some extraordinary circumstances to get the home water pressure up to 1,200psi. So like you say, if that happens, you've got bigger problems.
    – BMitch ♦
    Sep 26, 2014 at 2:10
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Here in upstate NY (it's -12 tonight which I will admit is unusually low) the risk of copper is freezing and bursting. That happened to me many times until I discovered Pex, which will expand several times its size without breaking and then return to its normal size. (Hmm, what does that bring to mind. But I digress.) Pex is so easy to work with and so much cheaper than copper, I don't know why you would not choose it. BTW, I have taken other measures to prevent freezing -- our hot water heating system is still copper but we have put in antifreeze, which works well. But, of course, you can't do that with domestic and live to see Superbowl 51. Use Pex.

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Copper developes pin holes leaks.... PEX doesn't. Copper's proven track record is pocked with major water leak damage.

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  • I've never seen copper fail unless it was a bad solder joint in the first place, or an ignored dielectric fitting. Copper also has antiseptic properties.
    – Mazura
    Oct 19, 2014 at 1:07
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Another big advantage to PEX is that if you live in a cold climate and are at risk of frozen pipes, PEX expands to accommodate the space the frozen water wants to take up, while copper will burst with small expansions of ice in the line.

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Copper piping has been around for at least 60 years and the only time you get pinholes in copper is because you probably used the wrong thickness of copper. If a solder joint is properly soldered then it will never leak. Ive been working on domestic hot water systems of every size for over 40 years and have never had any build up of any kind on the inside of the piping. That usually only happens on the larger street mains because the water moves slowly compared to a house. Copper has withstood the test for over 60 years. Pex can not make any such claims. It may be cheaper but it it may cost you in the long run. I would take copper over pex anytime UNLESS there is a good chance the pipes could freeze. I know pex can stretch much wider then copper and return to normal size.

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