Replace a Bathroom Sink Faucet

Replacing a bathroom faucet is one of the most satisfying small plumbing jobs you can do yourself. A leaking faucet, outdated finish, or simply wanting something that works better—any of these is reason enough to swap it out. The good news is that modern faucets are designed to drop into existing sink holes, which means you're not rearranging plumbing. You're just unbolting the old one and bolting in the new one. The work is mechanical, not mysterious, and the difference between a tired, dripping faucet and a clean, functional one is immediate and visible every morning.

1. Turn off the water supply. Locate the shut-off valves under the sink—there should be two, one for hot and one for cold. Turn both clockwise until they stop. If you don't have shut-off valves under the sink, you'll need to shut off the main water supply to the house and then open a faucet downstairs to relieve pressure. After the water is off, turn on the bathroom faucet to confirm the supply is truly shut down.
2. Disconnect the water lines. Place a bucket or towel under the supply lines to catch any remaining water. Using an adjustable wrench, loosen the compression nut on the hot water line first, then the cold water line. Turn by hand once they're loose enough. Gently pull the lines away from the faucet inlet ports and set them aside. This is where water will still drip, so keep your bucket ready.
3. Remove the mounting nuts. Most faucets are held to the sink from below by either two or three large brass or plastic nuts threaded onto studs that poke up through the sink deck. From underneath the sink, use an adjustable wrench or basin wrench to loosen and unthread these nuts. If the studs spin while you're unthreading, have someone hold the faucet body steady from above, or use pliers on the stud itself. Once the nuts are off, the faucet should lift away cleanly.
4. Clean the sink deck. With the old faucet out of the way, you'll see old caulk, corrosion, and mineral deposits around the faucet holes. Use a scraper or old credit card to remove caked-on material. Wipe the deck clean with a damp cloth and let it dry completely. This is your only chance to clean under where the faucet sat, so take advantage of it. A clean deck ensures the new faucet will seal properly and look finished.
5. Install the new faucet. Check the new faucet's instruction sheet for the order of assembly—some come fully assembled, others require you to thread the supply line connectors onto the faucet body first. Position the faucet over the holes so the base plate or mounting studs align. From underneath, thread the mounting nuts onto the studs and tighten by hand first, then use a wrench to snug them down evenly. Don't overtighten—just firm enough that the faucet doesn't move when you pull on it. The base should sit flush on the sink deck all around.
6. Reconnect the water supply lines. Take the hot water line and thread its compression nut onto the hot inlet port of the new faucet—usually marked with red or labeled. Thread by hand first to avoid cross-threading, then tighten with a wrench until snug. Repeat with the cold water line on the cold inlet port (usually blue or marked). Don't over-tighten compression fittings; they seal at the ferrule, not the nut. Snug is enough. Turn the shut-off valves back on slowly, checking immediately for leaks at both connections.
7. Test all handles and check for leaks. Turn on the hot handle and let hot water run for 10 seconds, then do the same with cold. Check the handle feel and the water pressure—make sure everything works as expected. Now inspect all connection points: the mounting studs where they enter the sink, and both water line connections underneath. Look for any drips or seeping. If you see water, turn the shut-off valves back off, tighten the leaking connection a quarter-turn with the wrench, and try again. Most leaks stop with one more quarter-turn.
8. Seal the base and clean up. Once you're confident there are no leaks, apply a bead of clear silicone caulk around the base where the faucet meets the sink deck. This keeps water from seeping down into the cabinet. Use a wet finger to smooth the caulk into a neat line. Let it cure for 24 hours before splashing the area with a lot of water. Wipe away any old caulk residue from the cabinet interior, dispose of packaging, and test the faucet one more time by running water and checking underneath.