I'm using PEX pipes for water tubing, but I'm not sure which sleeve type should I use for hot and cold water pipes.

Whats the difference between black, blue and red sleeves? and which should I be using for hot and cold water pipes

  • 1
    I think universally, red is hot, and blue is cold. – Gunner Feb 24 '13 at 20:16
  • the black got me confused and made me rethink this :) – Ahmad Saleh Feb 24 '13 at 20:17
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    Basically, the dye used in the plastic. Most of the stuff being sold around here is clear translucent (undyed) and as mentioned, when dyed is available, red-hot and blue-cold. – Fiasco Labs Feb 24 '13 at 22:11
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    I always get confused if the water line is both hot and cold! They need a blue and red striping pex. – DMoore Jun 19 '13 at 19:34
  • It's a good question though, since colors do matter in other places, such as electrical (gray) vs water (white) pvc. There are sometimes code implications with color, especially when they color things that go inside walls that nobody will see. – Nick Mar 12 '18 at 1:56

The color is just for convenience. Making it easy to identify hot and cold pipes under a house for instance. The chemical makeup and temperature ratings are identical besides the actual dye used to color it.


Color coding is an international mess. The only thing that's somewhat common is that purple means nonpotable water.

In residential plumbing, blue often means potable. Sometimes red means heated but that's still vague since there's a big difference between 120 °F and 212 °F.

Here's my policy:

  • Working on someone else's system? Ignore the colors and verify the connections for yourself.
  • Installing new plumbing? It's probably easiest to use one color everywhere and use tags/labels anywhere you want to mark something.
  • 1
    While color may be an international mess, it's often locally very clear. So likely not a problem for a plumber unless they tend to do work internationally. (Not that labeling isn't a bad idea...it certainly is, but I think, at least in North America, the red/blue standard is fairly consistent.) – DA01 Mar 23 '15 at 5:13
  • This seems like a good supporting argument for why switching everyone in the world to one international code is a bad idea. – Nick Mar 12 '18 at 1:58

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