Learn how to replace the cartridge in a water faucet by following a detailed tutorial about the process at TheFamilyHandyman.com, HomeDepot.com or BeJane.com. Over time, the cartridge or rubber O-ring within a water faucet wears out and starts to leak. By replacing these inexpensive parts, it's possible to avoid installing a new faucet.
Before attempting to replace the faucet cartridge, turn off the water to the faucet by twisting the water shut-off valves underneath the sink closed. Open the faucet fully and allow the water to drain out the fixture before proceeding. Remove the cap of the faucet handle with a flat-head screwdriver. Remove the screw underneath the faucet handle cap, and lift up to remove the entire handle from the faucet.
With a pair of water pump pliers, twist to the left to remove the retaining nut. Lift up to remove the water faucet spout. Using needle-nose pliers, remove any clips that hold the cartridge in place. Remove the existing cartridge and the surrounding O-rings and match the old parts to the new replacement parts for the specific faucet model.
Clean the pieces of the faucet to remove visible corrosion. Coat the O-rings with packing grease and push them firmly into place. Put the new cartridge in place, then use the existing cartridge clips to secure it. Replace the water faucet spout and use the retaining nut to hold the spout in place.
Finally, replace faucet handle, faucet screws and the faucet cap, ensuring to tighten each piece securely. Twist the water shut-off valves to the left to open the supply line, and the faucet should work normally.