How to replace a bathroom faucet
Short answer
To replace a bathroom faucet: count the holes in your sink and buy a faucet that fits them, close both valves under the sink and prove the faucet runs dry, unhook the supply lines and the lift rod, take the old faucet off from below with a basin wrench, keep the old drain or swap it, set the new faucet the way its sheet says, then flush the lines and test with the basin filled and drained. Difficulty 2 of 5; for a first-timer, plan on about half a day. Read the “Stop here” box below before step 1.
Draft guide written from standard practice, not yet reviewed by a licensed pro. Follow product labels where they differ.
Difficulty 2 of 5 · about half a day · careful
Stop here
Photo of your room, the look you pick, then this guide with the materials counted for your room.
What you need
- Bathroom faucet that fits your sink's holes
- Faucet supply lines (if the faucet's own are not attached)
- Plumber's putty or silicone, only if the faucet maker asks for it
- Pop-up drain (only if the faucet comes without one and the old drain leaks or does not fit)
Tools
- Basin wrench
- Adjustable wrench and channel-lock pliers
- Bucket, towels, headlamp
- Plastic putty knife and rubbing alcohol
- Penetrating oil, for a seized mounting nut
Step by step
Step 1 of 10
Read the new faucet's sheet and look under the sink
Find the new faucet's installation sheet: how many holes it needs, how it mounts, and what comes in the box — the supply lines, a deck plate, a drain. Empty the vanity and look at what you have: two shutoff valves, the lines to the old faucet, the lift rod behind the faucet, the drain and its trap. Photograph it all.
Step 2 of 10
Count the holes and check the fit
Count the holes in the sink and measure the spread between the outer ones. Compare with the faucet's sheet: a single-hole faucet, a centerset faucet, and a widespread faucet each fit a different layout. Extra holes take the deck plate; a missing hole is a stop — see the stop-gate.
Step 3 of 10
Water off at the valves and prove it
Close both shutoff valves under the sink gently, clockwise. Open the faucet, hot and cold: the flow should stop completely and stay stopped. If a valve will not close fully, weeps at the stem, or will not turn, stop here. Close the sink stopper or cover the drain so no small part falls in.
Safe to start?
- Both shutoff valves close fully — the faucet runs dry and nothing drips at the stems
- The new faucet fits the holes the sink has, or a deck plate covers the extra ones
- No hole will be drilled or enlarged in the sink or the top
- You know where the home's main water shutoff is
- Bucket, towels, and a headlamp under the sink, and the drain covered
Step 4 of 10
Unhook the supply lines and the lift rod
Bucket under the valves. Hold each valve body still with one wrench and undo the supply line nut at the valve with the other; stop at the first sign the pipe turns in the wall. Behind the drain, loosen the strap that joins the faucet's lift rod to the drain's pivot rod, so the lift rod comes up with the faucet.
Step 5 of 10
Take the old faucet off
From below, loosen the mounting nuts with the basin wrench; a few drops of penetrating oil help a seized one. Lift the faucet and its lines up and out from the top. Keep the old faucet until the new one works, in case you need to compare a part.
Step 6 of 10
Clean the deck and look at the cabinet floor
Scrape the old putty, caulk, and mineral crust off around the holes with the plastic putty knife, and wipe the deck with rubbing alcohol so the new base sits flat and seals. Look at the cabinet floor under the sink: stains or soft wood mean an old leak to find before the new faucet goes in.
Step 7 of 10
Keep the old drain, or swap it
If the old pop-up drain holds water, drains well, and does not leak, keep it and reuse its pivot rod. If the new faucet comes with its own drain and you swap it: bucket under the trap, undo the trap's slip nuts by hand, loosen the drain body's nut under the sink, and push the old drain up and out. Clean the drain hole, set the new drain with the sealant its sheet names, tighten its nut from below the way the sheet says, and put the trap back. Do not move the drain pipe in the wall.
Step 8 of 10
Set the new faucet on the deck
Follow the faucet's sheet: the gasket or the deck plate under the base, and putty or silicone only if the sheet asks for it. Feed the lines down through the holes, set the faucet square to the sink, and tighten the mounting hardware from below, evenly, until the faucet does not turn when you push the spout. A widespread faucet has separate handles and a spout joined under the sink by its own hoses, as the sheet shows.
Step 9 of 10
Connect the supply lines and the lift rod
Hot to the hot valve, cold to the cold, as the faucet marks them. Use the faucet's own lines or new ones, never the old ones. Route them without sharp bends, start each nut by hand, then give it the extra turn the line's package says. No thread tape on compression fittings. Join the lift rod to the pivot rod with its strap so the stopper opens and closes fully.
Step 10 of 10
Water on slowly, flush, and test
Take the aerator off, or follow the faucet's flushing steps. Open each valve slowly, run hot and cold to flush the lines, then put the aerator back. Fill the basin with the stopper closed, then let it drain, while you watch every joint under the sink with a dry paper towel. Lay dry towels under the valves and look again after an hour and the next day.
Quality check
- No drip at the valves, the supply lines, or around the faucet base after a day of use
- Hot and cold come out where the handle says, with a strong, even flow
- The stopper holds water in the basin and lets it drain, with no drip at the drain nut or the trap
- The faucet is tight to the sink and does not turn when you push it
- Both shutoff valves still close fully
Common mistakes
- Buying a faucet for the wrong holes. A faucet that needs more holes, or a different spread, than your sink has will not fit, and a sink or a stone top is not drilled at home. Count and measure the holes first; a deck plate covers extra holes, nothing covers a missing one.
- Forcing an old shutoff valve. Old multi-turn valves under a sink often snap or start leaking at the stem the moment you lean on them, and then the water to the bathroom cannot be closed. If a valve will not close gently and fully, stop: a plumber replaces it before the faucet comes off. Mistake #1 in this task.
- Cranking the slip nuts on the drain. Plastic slip nuts crack and their washers crush when cranked. Hand-tight plus a small turn, and snug a weeping joint a little at a time.
- Kinking or cranking the supply lines. A kinked line cuts the flow, and a cranked nut crushes its seal. Route the lines without sharp bends, start each nut by hand, then give it the extra turn its package says — no thread tape on compression fittings.
- Turning the water on with the aerator in. Bits of scale come loose after a faucet swap and clog a new aerator. Take it off, or follow the faucet's flushing steps, the first time the water runs.
Questions
How do I replace a bathroom faucet?
Close both shutoff valves under the sink and open the faucet: the flow must stop completely. Undo the supply lines at the valves, loosen the strap that joins the lift rod to the drain's pivot rod, and loosen the mounting nuts from below with a basin wrench. Clean the deck, set the new faucet with its gasket or deck plate, connect the faucet's own lines or new ones hand-tight plus the turn their package says, then flush the lines with the aerator off and watch every joint.
Will a new faucet fit my bathroom sink?
Count the holes in the sink and measure the spread between the outer ones, then compare with the faucet's sheet: a single-hole, a centerset and a widespread faucet each fit a different layout. A deck plate covers extra holes; nothing covers a missing one, and a sink or a stone top is not drilled at home.
Do I have to replace the drain when I change a bathroom faucet?
No. If the old pop-up drain holds water, drains well and does not leak, keep it and reuse its pivot rod. If the new faucet comes with its own drain and you swap it, undo the trap's slip nuts by hand, push the old drain out, set the new one with the sealant its sheet names, and put the trap back hand-tight plus a small turn: plastic slip nuts crack when cranked.
When should I stop and call a pro?
Like-for-like on the holes you have: the new faucet fits the holes in the sink, or covers the extra ones with its deck plate. Stop and call a plumber if: a shutoff valve under the sink will not close all the way, weeps at the stem, or will not turn — forcing an old valve usually breaks it; there is no shutoff valve under the sink; a supply pipe turns or moves inside the wall when you put a wrench on it; the old faucet's lines are soldered or hard-piped to the valves instead of screwed on; or the drain pipe at the wall is loose, cracked, or leaks when you touch it. A faucet that needs a new or bigger hole in the sink or a stone, quartz, or solid-surface top is not drilled at home — that is a new sink, or the fabricator's job. A wall-mounted faucet is work inside the wall, not a swap. A sensor faucet follows its own manual; one that needs power under the sink where there is no outlet is an electrician's call.