How to Connect PEX to a Fixture

Use compression fittings to connect PEX pipe to a fixture.
Use compression fittings to connect PEX pipe to a fixture. (Image: water pipes image by jeancliclac from

PEX pipe is made from polyethylene (HDPE), which is high density and flexible. It is manufactured in all the standard pipe sizes and can be used for either hot or cold water applications. PEX is made to replace copper pipe, cast-iron pipe and virtually every other composition of pipes for plumbing. Because PEX is made of plastic, it will remain flexible in any application. This quality makes PEX a water supply plumbing product that can be inserted into hard-to-reach areas, snaked over beams or supports and connected up to any fixture, wherever that fixture may be.

Things You'll Need

  • PEX piping, appropriate size
  • Compression fittings, appropriate size
  • Teflon pipe dope
  • Adjustable wrench and pipe wrench or locking pliers
  • Utility knife
  • Compression fittings

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Obtain a specific PEX compression fitting that will attach to your fixture. A standard fixture size is 1/2 inch, but there are many sizes and types of fixtures. Compression fittings for PEX pipe will either screw directly onto an existing fixture, such as a water feed line, or threaded sweat fittings can be soldered onto regular copper pipes first before attaching the PEX.

Coat the threads of the fixture with Teflon pipe dope, then screw the nut of the compression fitting over the threads on the fixture. Use an adjustable wrench to tighten it down firmly.

Push the end of the PEX pipe through a compression nut, then push a compression ring onto the end of the pipe. Firmly push the PEX pipe into the nut attached to the fitting, then hand-screw the compression nut on the PEX over the threads of the fitting nut.

Attach either a pipe wrench or a locking pliers onto the fixture nut, then tighten down the compression nut on the PEX pipe. Hold the pliers or pipe wrench steady so that there is no movement on the fixture nut, and tighten the compression nut securely.


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