Installing a New Bathroom Faucet: Step-by-Step

A new bathroom faucet can make a tired sink look brand new, and unlike a full vanity replacement, it's a project you can usually finish in an afternoon. The catch is that the tight, awkward space under a bathroom sink makes even simple steps feel harder than they should. Going in with a clear plan makes all the difference.

What you'll need

• New faucet (check the box for the number of holes it needs, usually 1, 3, or 4)
• Adjustable wrench and a basin wrench
• Plumber's putty or the faucet's included gasket
• Plumber's tape
• Bucket and towels
• Flashlight

Installation steps

1. Match your faucet to your sink. Before you buy anything, count the holes in your sink deck and measure the spacing between them. A single-hole faucet won't cover a spread-fit sink, and a three-hole widespread faucet won't work on a single center hole without an adapter plate. Getting this wrong is the single most common reason people end up making a return trip to the store mid-project.
2. Shut off the water and clear the space. Turn the hot and cold shutoff valves under the sink clockwise until they stop, then open the faucet to relieve pressure and drain any water left in the lines. Empty the cabinet and lay towels down. This is also a good moment to grab a flashlight, since you'll be working mostly by feel.
3. Disconnect and remove the old faucet. Use your adjustable wrench to disconnect the supply lines from the shutoff valves, then loosen the mounting nuts holding the faucet to the sink deck, usually from underneath with a basin wrench. Once the nuts are off, lift the old faucet out from above. Old faucets often leave a ring of dried putty or caulk behind, so scrape the sink deck clean so the new faucet sits flat.
4. Set the new faucet and gasket. Most modern faucets come with a rubber gasket that seals against the sink, which means no plumber's putty needed. If yours doesn't include one, run a thin bead of putty around the base instead. Feed the faucet's tailpieces and supply lines down through the mounting holes, then secure the faucet from below with the mounting nuts. Snug them by hand first, then finish with the wrench, careful not to overtighten and crack the gasket.
5. Connect the supply lines. Wrap the threads of the faucet's tailpieces with plumber's tape, then connect your new flexible supply lines between the faucet and the shutoff valves. Hand-tighten, then give each connection a quarter turn with the wrench. Snug is the goal here, not as-tight-as-possible.
6. Turn the water back on and check for leaks. Open the shutoff valves slowly and watch every connection point for a minute or two. Run the faucet on hot and cold, check underneath again, and look at the base of the faucet on top of the sink deck too. A small drip at a connection usually just means it needs another quarter turn.

A note on variations

Vessel sinks, wall-mounted faucets, and faucets with separate handles each have their own quirks, and some widespread faucets require connecting a hidden bar between the handles and the spout before installation. If your setup doesn't match a standard drop-in configuration, read the manufacturer's instructions fully before you start pulling anything apart.

Most of this job comes down to patience in a cramped space rather than technical difficulty, but if you run into a stuck supply line, a mounting nut that won't budge, or a leak that won't stop no matter how many times you tighten it, it's worth calling ProFlow Plumbing rather than forcing it. A stripped fitting under a bathroom sink is a much bigger headache than the faucet swap you started with.