The shower faucet cartridge is the piece of pipe that connects the handle that changes the water supply from tub to shower with the inner valve. If the handles in your shower do not turn the water all the way on or off, the cartridge needs to be replaced. With a few tools and a little patience, this is an easy DIY task.
Step 1 - Prepare the Shower
The cartridge may also need to be replaced if water sprays out of the handle. There are three handles in a typical shower: cold water, hot water, and the shower faucet. Before replacing the faucet cartridge, close the bathtub drain to prevent parts from falling in. Then turn off the hot and cold water by turning the shut off behind each handle with a flat head screwdriver. Now you are ready to start the process.
Step 2 - Remove Faucet Handle
Start by popping the faceplate off the handle with a small knife or screwdriver to expose the screw. Screws in the bathtub are usually made of soft copper, so use the right size screwdriver to prevent damage when you remove them or the heads can get stripped.
Step 3 - Remove the Decorative Ring
There is usually a ring or faceplate that surrounds the cartridge. This will need to be removed to access the shower faucet cartridge. You can remove this by turning the ring with a standard wrench. You may need to use a knife to cut a line into any caulking that is around the ring.
Step 4 - Remove the Cartridge
Be patient while removing the actual cartridge. Start by lubricating the nut that holds it in place with WD40 or a similar lubricant. Next, using the appropriate tool, remove this nut. The cartridge is now free to be removed. It will come slowly; use a wrench and pull lightly while it comes out of the surround.
Step 5 - Select a New Cartridge
Not all shower faucet cartridges are the same. Take the old cartridge to your local hardware store for a direct match. You will see the wear on the old cartridge compared to the new one. Wear and oxidation on an old cartridge causes water to leak around the area.
Step 6 - Install the New Cartridge
You may choose to lubricate the cartridge again with WD40 or simple petroleum jelly. It is recommended that you use plumber's tape around the threads of the nut that will hold the new cartridge in place. This helps form a better seal. Tighten the cartridge. You will want to test for leaks by turning on both the hot and cold water. Try the shower and the bathtub. If you are satisfied, clean up and put away your tools.