How to Replace a Moen Shower Valve Cartridge

A Moen cartridge shower faucet uses a plastic valve to regulate the flow of water through the shower head. If the shower uses a single cartridge, that cartridge is also responsible for mixing the flow of hot and cold water to the desired temperature. Over time, the internal components of a cartridge faucet corrode, particularly the O-ring, located on the bottom of the cartridge. Once the O-ring becomes damaged, water will leak from the bottom of the faucet's handle, even when the shower is not being used. Thankfully, replacing a Moen cartridge faucet is a simple process.

Replace a Moen Shower Valve Cartridge
  1. Turn off the shower's main water supply at the shutoff valve located next to the water meter.

  2. Remove the faucet's handle. Pry off the decorative cap located at the center of the faucet's handle with the blade of a flat-head screwdriver. Remove the handle's retaining screw with a Phillips-head screwdriver, then pull the handle away from the faucet valve.

  3. Remove the plate that rests against the shower wall behind the faucet's handle. Unscrew the plate's retaining screw, then pull the plate away from the wall.

  4. Unscrew the faucet valve's retaining nut. Insert a shower stem socket through the shower wall onto the nut and turn it counterclockwise.

  5. Grasp the tip of the shower cartridge with a pair of pliers, then pull the cartridge straight out of the wall. Insert the replacement cartridge into the wall and tighten the valve's retaining nut with the shower stem socket.

  6. Place the valve's plate against the wall. Tighten the plate's retaining screw with a screwdriver.

  7. Slide the faucet's handle over the faucet. Tighten the handle's retaining screw through the center of the handle. Press the handle's decorative cap over the handle's retaining screw. Turn on the water supply to complete the replacement.

About the Author

John Stevens has been a writer for various websites since 2008. He holds an Associate of Science in administration of justice from Riverside Community College, a Bachelor of Arts in criminal justice from California State University, San Bernardino, and a Juris Doctor from Whittier Law School. Stevens is a lawyer and licensed real-estate broker.