How to Replace a Bathroom Sink Faucet

Replacing a bathroom sink faucet is one of the most rewarding plumbing projects a homeowner can tackle. It transforms how a sink feels and functions, costs less than a plumber's visit, and requires no special skills—just patience and the willingness to get under the cabinet. The job splits into two real phases: disconnecting the old faucet (which is mostly persuasion and penetrating oil) and installing the new one (which is fitting and sealing). Done right, you walk away with a faucet that looks clean, feels solid, and won't drip or leak. Done wrong, you learn about water damage. The difference is attention to detail and not forcing anything.

  1. Shut Off Water First. Look under the sink for two shut-off valves—one for hot water, one for cold. They're usually oval knobs or small levers on the copper or PVC lines coming up from the wall. Turn both clockwise (or pull down if they're lever-style) until they stop. Open the faucet upstairs to release any pressure in the lines. If you don't have shut-off valves under the sink, you'll need to shut off the main water supply to the house.
  2. Loosen Corrosion First. If you can see the bolts holding the old faucet from underneath the sink, spray them liberally with penetrating oil (WD-40 or equivalent). The faucet bolts sit in damp conditions and corrode. Even if they look fine, spray them anyway. Wait 20 minutes before you touch them.
  3. Free The Supply Lines. Place a towel under the sink to catch residual water. Use an adjustable wrench to loosen the compression nuts where the faucet lines connect to the shut-off valves. Loosen by hand after the wrench breaks them free, then pull the lines away. If the nuts won't budge, spray them again and wait. Don't force them—stripped nuts mean a trip to the hardware store for new shut-off valves.
  4. Document Before Disconnect. Some faucets come with an integrated pop-up drain assembly that connects to the faucet body. If yours does, look under the sink for a thin rod or clevis strap connecting the faucet to the drain assembly. Unscrew the clevis screw and slide the rod out. If your drain is independent, skip this step.
  5. Extract Mounting Bolts. From underneath the sink, you'll see nuts holding the faucet to the counter. Usually there are two, sometimes three. Use an adjustable wrench or basin wrench (a specialized tool that grips bolts in tight spaces) to unscrew them. If a bolt spins without loosening, the faucet stud is turning. Ask someone to hold the nut steady from above while you turn the bolt from below. Once loose, unscrew by hand.
  6. Coax Out The Old Faucet. Once all bolts are removed and lines are disconnected, lift the faucet straight up and out of the sink. It may resist—there's old caulk or mineral deposits holding it. Wiggle gently and work a putty knife around the base to break the seal. Don't yank; patience wins here.
  7. Clear Away Old Buildup. With the old faucet out, you'll see the mounting holes and old caulk residue. Scrape away all old caulk and mineral buildup with a putty knife. Wipe the deck clean with a wet cloth and let it dry completely. A clean surface means your new faucet won't move or shift after installation.
  8. Position New Faucet Perfectly. Most new faucets come with a rubber gasket that goes on top of the counter, under the faucet base. Slide the gasket onto the faucet studs, then insert the faucet into the mounting holes. From underneath, hand-thread the bolts back on. Don't tighten yet—just snug them enough that the faucet sits level and centered.
  9. Tighten With Balance. Using your wrench, tighten the bolts in an alternating pattern (left, then right, then left again). This distributes pressure evenly and keeps the faucet from tilting. Tighten until snug—the gasket compresses and the faucet is solid. Don't overtighten; you'll crack the sink or strip the bolts.
  10. Reconnect Water Supply. Reconnect the hot and cold supply lines to the faucet inlet ports. Hand-thread the compression nuts first, then use your wrench to tighten them. Tighten until snug, then an additional quarter-turn. Don't use excessive force—these connections need to seal but not be crushed.
  11. Restore Drain Function. If your faucet has an integrated pop-up drain, reconnect the clevis rod to the faucet body and tighten the clevis screw. The rod should move freely up and down. Adjust the rod position if the pop-up moves too stiffly or won't seal when closed.
  12. Check For Leaks Thoroughly. Turn on both shut-off valves under the sink (counterclockwise or push up if they're levers). Open the faucet handle and let water run for 30 seconds to flush air from the lines. Check for leaks at every connection point—supply lines, faucet base, and pop-up drain. Tighten any connection that drips slightly.
  13. Seal Against Water Damage. Once you're confident there are no leaks, apply a continuous bead of silicone caulk around the base of the faucet where it meets the sink deck. This keeps water from seeping under the faucet and rotting the cabinet. Smooth the caulk with a wet finger and let it cure per the tube instructions (usually 24 hours before using the sink heavily).