How to Replace a Shower Cartridge in 7 Simple Steps

First, you'll need to remove the shower handle to see if the cartridge is the reason your shower is leaking. Use a flathead screwdriver to pry the plastic cap off the shower handle.

Every handle is a little different. If it's not apparent by looking (e.g., a screw is attached to the handle), do an online search for the make and model of your handle with the term "removal” to find instructions for removing it.

If your shower handle design is a single lever, you might need an Allen wrench to loosen the screw underneath and remove the handle.

Next, you'll need to remove the escutcheon, the piece of metal (usually shaped like a ring or sphere) that covers the hole in your shower's wall. It’s typically attached to the wall with screws. Set it aside with all the screws for reinstallation later.

Behind the shower handle and flat metal plate, you should find a clip holding the shower cartridge in place. Again, different models will look different. Some are covered with a metal sleeve, while others are exposed. 

Use a flathead screwdriver to unhook the clip holding the cartridge in place. Set it aside in a safe place. While many new shower cartridges come with a retainer clip, some do not. If that’s the case, you can simply reuse the original clip.

Locate your shower cartridge pulling tool. If your model is older, you can simply remove it with pliers. Hook the puller tool onto the edges of the cartridge and slowly turn until it loosens.

Note the position of the cartridge before you begin unscrewing it. You'll need the new shower cartridge to be in the same orientation to ensure hot and cold water comes out the same way when you turn the handle.

In some cases, a shower cartridge's O-rings may simply have mineral deposits on them that cause them to leak. You can try removing the mineral deposits and reinstalling the O-rings before buying a new kit. 

Otherwise, position the new shower cartridge into the vacant space. If your new shower cartridge comes with a model-specific tool for installation, use it. Make sure it's tight and in the same position as the old one was.

Once the new cartridge is in place, turn the water supply back on and test your work. If there's still a leak, you may need to double-check that everything is tight.

If you still notice leaks but are confident it's not the shower cartridge—for example, maybe you notice only a few beads of water running down, suggesting that a pipe is loose or maybe your shower is just old—you might choose to reinforce the edges of your escutcheon and valve with silicone caulk. Read the directions carefully and adhere to dry times before retesting.

Retrace the steps you followed earlier: re-install the escutcheon and screw the shower handle back on. To protect your new investment, consider adding a bit of plumber's grease to prevent erosion over the surface of your new shower cartridge. A tube costs $2 to $5 at home improvement stores.