I saw a house for sale today and my realtor and I couldn't figure out what this was attached to the water heater, some kind of water piping/tubing. We'll get to the bottom of it with the inspection, just impatient to know what on earth this is. House built in 1984.enter image description here

  • 25
    Your realtor has never seen that before? It's an incredibly common plumbing material usually called PEX.
    – Matthew
    Dec 30, 2019 at 2:24
  • 1
    Those are your water pipes. The material in question is called PEX. It is becoming increasingly common to see it used in homes. I just got done re-piping my entire downstairs with PEX. The short white one with the shut off valve and thin copper is likely a line for the ice maker in your fridge.
    – MonkeyZeus
    Dec 30, 2019 at 13:19
  • 2
    Are the red ones hot then? Dec 30, 2019 at 15:05
  • 12
    Why not put your answers in the box labeled “answer” instead of the one labeled “comment”?
    – WGroleau
    Dec 30, 2019 at 16:37
  • I'll note that this "manifold" scheme is rarely used with regular copper or glued plastic piping, but with PEX it's a lot easier to install (fewer joints) and, for the hot water, it delivers water at temp a lot faster.
    – Hot Licks
    Dec 30, 2019 at 22:43

2 Answers 2


It looks like PEX and has the white ring things that go over Uponor ProPEX style connectors. Here is a video of the material in use, pay attention to the expansion tool: https://www.youtube.com/watch?v=AXYONkaxzv8

You should confirm this observation by noting any markings printed on the tubing, they should say PEX somewhere. The house was built right in the middle of the polybutylene era, you want to be absolutely sure it is not that.

PEX would definitely not be original to the house as it did not exist in 1984. Why the piping was replaced would be a good question for the seller, it might actually be replacing polybueylene. https://www.nachi.org/pb.htm


That would be your water distribution system, aka supply plumbing. Cross linked polyethlene, or PEX for short; Using a manifold arrangement.

Most likely the red ones are hot water, the white ones are cold.

Only gets confusing if there's also a hydronic heating system also using PEX, but no more so than when they were all copper, or iron.

  • Might be worth mentioning you can "Google" for "PEX Manifold" to see various types of manifolds like these. Dec 30, 2019 at 14:14
  • @DerKommissar - Actually, that should be "manifold types of manifolds".
    – Hot Licks
    Dec 31, 2019 at 1:35
  • Well done, @HotLicks :)
    – bitsmack
    Dec 31, 2019 at 9:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.