- Close both shutoffs under the sink. Open the faucet until the water stops. If a shutoff will not close or spins free, stop and call someone. Forcing an old valve breaks the pipe inside the cabinet.
- Cover the drain with a cloth. Small parts fall in there.
- On an old compression faucet, remove the handle screw, lift the packing nut, and replace the rubber washer on the stem. Reassemble it snug, not crushed.
- On a single-lever faucet the inside is a cartridge. Write down the model or take the old cartridge to the store. The cartridge nut comes off with a wrench, not with pliers on the chrome.
- Open the shutoff slowly and dry each joint with paper. If the paper gets wet, tighten a little more. If water comes out around the spout base, the spout O-ring is worn.
Stop if water is coming from inside the wall, if the shutoff will not hold, or if the cabinet floor is swollen. That is past a washer.