How to Install a Bathroom Faucet

Open the box and spread everything out on the counter where you can see it. You should have the spout, both handles, the mounting hardware, and a pop-up drain assembly with a bag of small parts. Read the instruction sheet once, even if you think you know the drill.

Knowing what each piece does before you crawl under the sink saves a lot of back and forth. Set the small parts aside in a cup so nothing rolls off into the vanity.

Turn off the water at the two shutoff valves under the sink and open the faucet to drain the lines. Put a bucket or towel down to catch drips. Disconnect the supply lines from the faucet shanks with an adjustable wrench.

Reach up behind the basin with a basin wrench and back off the mounting nuts holding the old faucet in place. Once they're loose, lift the whole faucet up and out of the deck. Scrape off any old putty or grime around the holes so the new faucet seats clean.

Drop the spout into the center hole and each handle into the outer holes. Line them up so the handles face forward and the spout points into the basin. On a widespread set, the three pieces mount separately but connect underneath.

Hold the faucet steady on top while you thread the mounting nuts on from below by hand. Snug each one with a basin wrench, checking from above that nothing spun out of alignment while you tightened.

Roll a rope of plumber's putty and press it around the underside of the drain flange. Push the flange down into the drain hole from inside the basin so the putty squeezes out a little all the way around.

Hold the flange down while you thread the drain body onto it from below, with the pivot-rod opening pointed toward the back wall. Wipe away the putty that squished out so the finished flange looks clean.

Snug the locknut on the drain body up against the underside of the basin so the flange sits tight and won't leak. Don't crank it, just firm.

Push the pivot rod through the opening in the drain body so it catches the stopper inside. Slide the flat clevis strap onto the lift rod that runs down from the top of the faucet, then clip the pivot rod into a hole on the strap. Lift and drop the rod on top to make sure the stopper opens and closes.

Connect the P-trap to the drain tailpiece coming down from the new drain and to the drain stub in the wall. Slide the slip nuts and beveled washers onto the pipes in the right order before you thread anything together.

Hand-tighten each slip nut, then give it a small turn with pliers or a wrench. The trap should hang level with a gentle downward slope toward the wall so it drains fully.

Thread a braided supply line onto each faucet shank and run the other end to its shutoff valve. Match hot to the left shank and cold to the right so the handles work the way you expect.

Hand-tighten both ends, then snug them a little more with a wrench. Braided lines seal on a rubber washer, so you don't need much muscle. Overtightening is how you crack a fitting.

Open both shutoff valves slowly and let the faucet run hot and cold. Watch the connections underneath with a flashlight for any drips at the supply lines, the drain body, and the trap.

Fill the basin and pull the stopper to check that it holds water and drains clean. If you spot a slow leak, snug that one fitting a touch more rather than tightening everything. A finished install runs quiet, seals tight, and looks like it was always there.