How to Install a New Bathroom Faucet | Step-by-Step Swap

Swapping a tired bathroom faucet is one of the most satisfying DIY upgrades in a home. The job looks intimidating because of all the hardware under the sink, but the process is straightforward: shut off the water, remove the old faucet, clean the surface, set the new one, and reconnect everything. Here’s the exact sequence that works for standard US bathroom sinks, drawn from Home Depot’s and Moen’s official instructions.

Tools and Supplies You’ll Need

Gather everything before you start so you’re not hunting for tools mid-job. Most of this is standard household gear:

• Adjustable wrench and basin wrench (for tight nuts under the sink)
• Bucket and old towels for residual water
• Plumber’s putty or silicone caulk (only if your faucet’s instructions call for it)
• Flashlight to see into the cabinet
• Penetrating oil for stubborn nuts, worth having on hand

Your new faucet should arrive with mounting hardware, supply lines, and a gasket or escutcheon. Open the box and confirm everything is there before you shut off the water.

Removing the Old Faucet

Start with the only step that really matters for safety: turn off the hot and cold shutoff valves under the sink, turning each clockwise until it stops. If your sink has no shutoff valves, close the main water valve for the house instead, then open the faucet to relieve pressure and drain the lines.

Disconnect the supply lines with your adjustable wrench, keeping the bucket handy because trapped water will spill. Work from the top down: disconnect the lines first, then loosen the mounting nuts or wing nuts underneath with the basin wrench, and lift the old faucet out. If the nuts are corroded or stuck, apply penetrating oil and wait a few minutes rather than forcing them, which can strip the threads.

Clean the sink deck thoroughly once the old unit is out. Scrape away old putty, silicone, and mineral deposits; a clean surface is what lets the new gasket seal properly. A putty knife works well, but be careful not to scratch the sink finish.

Installing the New Faucet

Follow the preassembly steps in your faucet’s manual before positioning it, because included parts and the order of assembly vary by model. Some faucets arrive partially assembled; others need the supply lines or drain pop-up attached first.

Lower the faucet into the mounting holes with the gasket or escutcheon aligned properly. Only apply plumber’s putty or silicone caulk if the manufacturer’s instructions specify it; using sealant where it isn’t called for can interfere with the gasket’s seal and cause more problems than it prevents.

From underneath, thread the mounting nuts on and tighten them evenly, alternating sides, until snug. Avoid overtightening; it can crack the faucet base or strip the mounting threads. Reconnect the supply lines with hot on the left and cold on the right, standard US orientation, and tighten each fitting until snug—again, no more.

If your faucet includes a pop-up drain assembly, now is the time to install or adjust it, since it sits behind the faucet body and is difficult to reach once everything is in place.

Turning the Water Back On Without a Mess

This is the moment most people rush, and it’s exactly where leaks happen. Open both shutoff valves slowly and check each connection as the water comes back. Look at the supply-line fittings, the mounting area, and the pop-up drain for drips. Tighten any leaky fitting just a quarter-turn at a time and recheck; if a connection drips continuously or the fitting feels stripped, shut the water off and inspect the threads for damage.

Once everything is dry, flush both hot and cold water for a full minute to clear debris from the lines, then remove and clean the aerator to clear any particles that landed there. Your new faucet should run smoothly with no drips and no puddles under the sink.

A quick note on fit: common US bathroom faucets use one-hole, center-set, or widespread 3-hole configurations, and neck height matters for basin clearance. Measure your sink’s hole spacing and depth before you buy. If you’re shopping for a replacement, see our roundup of faucets designed for easy installation to save yourself the headache of tricky hardware.