How to Repair a Dripping Faucet Cartridge

Drips are more than just a rhythmic annoyance; they are a constant drain on your water bill and a silent wear-and-tear factor on your plumbing fixtures. Most modern single-handle or double-handle faucets rely on a plastic or brass cartridge to manage the flow and mix of water. When the seals inside this component degrade, water finds a way out, usually appearing as a steady leak from the spout or a seep at the base of the handle. Fixing this is a mechanical task that requires more patience than raw strength. The key to a successful repair is identifying the precise model of your faucet before you start. If you attempt to use a generic cartridge, the faucet will likely continue to leak or fail to seat correctly. Take your time during disassembly, keep your small parts organized, and you will find that a smooth-functioning faucet is a simple matter of swapping one small part.

  1. Kill the Water First. Locate the water supply valves under the sink and turn them clockwise until they stop. Open the faucet handle to bleed out remaining pressure and ensure no water is left in the lines.
  2. Free the Handle. Pry off the decorative cap on the handle, usually with a flat-head screwdriver or a thin knife. Use an Allen wrench to loosen the set screw inside and pull the handle assembly straight off.
  3. Unscrew the Bonnet. Use a pair of adjustable pliers or a wrench to unscrew the decorative bonnet nut holding the cartridge in place. Turn counter-clockwise, keeping the tool perpendicular to avoid marring the finish.
  4. Extract the Cartridge. Grasp the top of the cartridge with pliers and pull it straight up. Some cartridges have a retaining clip that must be pulled out horizontally with needle-nose pliers first.
  5. Polish the Seat. Look inside the faucet body and clear out any mineral buildup or debris using a soft brush or vinegar-soaked rag. Ensure the interior is smooth and clean so the new O-rings seat perfectly.
  6. Seal and Restore. Insert the new cartridge, aligning the notches or tabs with the faucet body. Replace the bonnet nut, tighten it firmly but not overtight, and reattach the handle before slowly turning the water supply back on.