How to Replace a Bathroom Faucet Cartridge

Drips are the classic indicator that a faucet cartridge has reached the end of its lifespan. Over time, the internal rubber seals or ceramic discs wear down, allowing water to bypass the valve even when the handle is firmly shut. Replacing the cartridge is a surgical repair that saves you from replacing the entire faucet assembly, provided you have the right replacement part in hand before you start. Success in this project relies entirely on matching your existing hardware. Faucets vary wildly by manufacturer, and internal components are rarely interchangeable. By taking the time to disassemble the unit carefully and identifying the cartridge style before heading to the store, you ensure a leak-free result that restores smooth, quiet operation to your vanity.

  1. Kill the Water Supply. Locate the shut-off valves under the bathroom sink and turn them clockwise until they stop. Open the faucet handles to bleed out remaining pressure and confirm the water supply is truly cut off.
  2. Expose the Set Screw. Pry off the decorative cap on the handle to expose the set screw underneath. Use an Allen wrench or a small screwdriver to loosen the screw, then pull the handle straight off the faucet body.
  3. Document Before You Disassemble. Unscrew the decorative trim or bonnet nut holding the cartridge in place. Use a wrench with a cloth wrapped around the jaws to avoid scratching the finish, and remove the retaining clip if one is present.
  4. Grip and Pull Straight Up. Pull the old cartridge straight up and out of the faucet body. If it is stubborn, use a pair of pliers to grip the top, but be careful not to crush the plastic housing inside the valve body.
  5. Align Tabs and Lubricate. Compare your old cartridge to the replacement to ensure the length, diameter, and seal placement are identical. Insert the new cartridge, aligning the guide tabs with the corresponding slots in the faucet body.
  6. Test and Verify No Leaks. Tighten the bonnet nut securely, replace the handle, and tighten the set screw. Slowly turn the water supply back on and check the faucet for leaks through multiple handle cycles.