How to Cap a Water Pipe With a Push-On Fitting

  • 01 of 05

    Why Caps Are Needed

    Capping a water pipe
    Aaron Stickley

    Temporarily capping water-supply pipe is often necessary during a kitchen or bathroom renovation. For example, when replacing cabinets you may find that the water supply pipes extend through the back or bottom floor of a sink cabinet. Rather than cutting out a large section of the cabinet to remove it, it is usually far easier to cut off the ends of the pipes and cap them with easy-to-use push-on fittings that will work with copper, CPVC, or PEX plumbing pipes. 

    Tools and Materials You Will Need

    • Tubing cutter or hacksaw
    • Emery cloth
    • Metal file (if needed)
    • Tape measure
    • Marker
    • Push-on pipe caps
    Continue to 2 of 5 below.
  • 02 of 05

    Shut Off the Water

    Shut off the water supply to the house. Since you'll be cutting the water pipes behind or below the shutoff valve on each pipe, you must shut off the water at the main shutoff valve. Drain residual water and pressure from the pipes by turning on an outside spigot or a faucet that is lower than the pipes you are working on (such as on a basement washtub). This minimizes the amount of water that spills out of the pipes when you cut into them.

    Continue to 3 of 5 below.
  • 03 of 05

    Cut Off the Pipes

    Clean copper pipe before capping
    Aaron Stickley

    Cut off the water pipes, using a tubing cutter if you have enough room to rotate the tool around the pipe. You can also use a hacksaw, but be careful to make a clean, square cut to ensure a proper seal with the push-on fittings. Leave as much pipe as possible so you won't have to lengthen it later when reconnecting the fixture.

    Clean the end of each cut pipe with emery cloth—it must be smooth and free of old solder or other material. If you cut the pipes with a hacksaw, file off any rough edges before cleaning with emery cloth.

    Continue to 4 of 5 below.
  • 04 of 05

    Cap the Pipes

    Cap water pipe with push on fitting
    Aaron Stickley

    Measure from the end of each pipe and make a depth marking, as directed by the push-on fitting manufacturer. The mark will tell you when the fitting is pushed on all the way, which is essential for a proper seal.

    Push the pipe cap onto the pipe until its edge reaches the depth mark.

    • Note: Push-on fittings work for copper, CPVC, and PEX water pipe. Most include a stiffener—a small plastic cylinder—that slips into the end of the pipe to provide rigidity to PEX tubing. It is not required with copper or CPVC pipe.
    Continue to 5 of 5 below.
  • 05 of 05

    Test the Capped Fittings

    Cap copper pipe with push on fitting
    Aaron Stickley

    Turn the water back on and check the cap connections for leaks.

    Push-on fittings can be temporary or permanent. Most include a release feature that allows you to remove the fitting with a special tool, which is usually a simple plastic device that you push against the fitting to depress a release collar and slip off the fitting. Always use the manufacturer's tool to remove the fittings.