How to Fix a Leaky Single-Handle Faucet (Ball-Valve Type)

The first and most critical step is to prevent water from flowing to the faucet while you work. Locate the two shutoff valves under the sink, one for hot water and one for cold. Turn the handles clockwise until they are fully closed. If there are no shutoff valves under the sink, you will need to turn off the main water supply to the entire house. After closing the valves, turn the faucet handle to the 'on' position in the middle (mixed hot/cold) to relieve any residual water pressure and confirm that the water is indeed off. Place a towel in the sink basin over the drain to catch any small parts.

Locate the small set screw that secures the handle to the faucet body. It is often hidden behind a small decorative plastic or metal cap on the front or side of the handle, which may be marked with a red/blue hot/cold indicator. Carefully pry this cap off using a small flathead screwdriver or a pick. Inside, you will see the set screw. Use the appropriate size Allen wrench (hex key) to turn the screw counter-clockwise. You only need to loosen it a few turns; it does not need to be completely removed. Once loose, lift the handle straight up and off the faucet body.

With the handle removed, you will see a chrome dome-shaped cap. This cap threads onto the faucet body and holds the internal parts in place. Wrap the jaws of a pair of channel-lock pliers with electrical tape or use a rag to protect the finish, then grip the cap and turn it counter-clockwise to unscrew it. Lift the cap off. Underneath, you will see a plastic cam and a rubber packing. Simply lift the cam, packing, and the stainless steel ball straight out of the faucet body. Note the small slot on the side of the ball and how it aligns with a small pin inside the faucet body; this is crucial for reassembly.

Look inside the now-empty faucet body. You will see two small circular rubber seats, each with a small conical spring underneath it, recessed into ports. These are the primary cause of most leaks. Use a small flathead screwdriver or a pick tool to reach into the faucet body and carefully pry out each of the old rubber seats and the springs beneath them. Take the new seats and springs from your faucet repair kit. Place a new spring (narrow end down) into each port, and then place a new rubber seat over each spring, pressing it down gently into place with your fingertip or the eraser end of a pencil. The cupped side of the seat should face up.

Begin reassembling the faucet in the reverse order of disassembly. First, drop the stainless steel ball back into the faucet body. Make sure the small slot on the side of the ball aligns perfectly with the pin inside the faucet body. Next, place the new plastic cam and packing (from the kit) over the ball. The small lug on the cam should fit into the notch on the side of the faucet body. Now, screw the dome-shaped cap back on by hand until it is snug. Use the channel-lock pliers (with protected jaws) to give it a final quarter-turn to tighten it securely. Do not over-tighten.

Place the handle back onto the cam stem, ensuring it is properly seated. Tighten the set screw with the Allen wrench until it is snug. Replace the decorative cap. Now, slowly turn the water back on at the shutoff valves under the sink, turning them counter-clockwise. Turn them on one at a time and only part-way at first. Check for any leaks around the base of the handle and spout. If there are no leaks, open the valves fully. Move the faucet handle through its full range of motion—hot, cold, and mixed—to ensure proper operation and to check for any final leaks. If the leak is gone, the repair is complete.