How to Replace a Leaky Bathroom Sink Faucet

Faucets are the hardest-working fixtures in your home, and eventually, the internal seals wear out, turning a steady drip into a costly water-waster. While a minor drip might be a simple O-ring fix, replacing the entire unit is often the smarter long-term play, especially if the finish is pitted or the internal valves are corroded beyond repair. Done well, a faucet replacement is a clean, dry, and straightforward job that breathes new life into your vanity. The trick is preparing for the tight, awkward space underneath the basin. If you work methodically and clear the area of clutter before you start, you can swap out a faucet in about an hour without needing to call in a professional.

  1. Stop the water flow. Locate the shut-off valves under the sink and turn them clockwise until they are fully closed. Open the faucet handles to bleed off any remaining water pressure in the lines.
  2. Detach the water supply. Place a bucket underneath the supply connections to catch residual water. Use an adjustable wrench to loosen the nuts connecting the supply lines to the shut-off valves, then disconnect them from the faucet shanks.
  3. Extract the old faucet. Reach behind the basin and use a basin wrench to unscrew the mounting nuts holding the faucet to the sink deck. Once loose, pull the faucet assembly upward and out from the top of the sink.
  4. Clear the mounting area. Scrape away all old putty or mineral buildup from the mounting holes using a plastic putty knife. Wipe the area clean with a damp cloth or denatured alcohol to ensure the new seal sits flat.
  5. Set the new faucet. Place the new faucet gasket or a bead of plumber's putty around the base of the faucet. Feed the supply lines and shanks through the mounting holes, then hand-tighten the mounting nuts from underneath.
  6. Tighten all connections. Attach the new supply lines to the shut-off valves and the faucet shanks. Tighten the nuts firmly, but be careful not to overtighten, which can crack plastic components or damage rubber washers.
  7. Verify the installation works. Slowly open the shut-off valves and check every connection point for moisture. Run the faucet for a full minute, watching underneath the sink for any slow drips.