Replace a Leaking Bathroom Sink Faucet

A leaking faucet wastes water and money—sometimes thousands of gallons a year from a slow drip you barely notice. The good news is that replacing a bathroom sink faucet is one of the most straightforward plumbing repairs you can do yourself, requiring only basic tools and a small amount of patience working in tight spaces. A new faucet costs between $40 and $200 depending on style, and installation takes less than an hour. When you're done, you'll have a fresh, functional faucet and the knowledge that you saved the cost of a service call. The key to success is taking your time under the sink, keeping track of small parts, and not forcing anything. Water shutoff valves can be stubborn after years of sitting still, so treat them gently. If you encounter a valve that won't budge or corrosion that makes disconnection difficult, you know when to call a plumber—but nine times out of ten, you'll finish this job on your own.

1. Shut off the water supply. Look under the sink for the small shutoff valves on both the hot and cold supply lines. Turn each valve clockwise until it stops—you should feel gentle resistance, not a hard stop. If the valves are stuck or missing, locate your main water shutoff and turn that instead. Turn on the faucet briefly to confirm the water is off.
2. Clear the space and disconnect the supply lines. Remove everything stored under the sink—cleaning supplies, trash, organizers. Put a bucket or towel under the supply line connections to catch residual water. Using an adjustable wrench, loosen the compression nuts connecting the supply lines to the faucet base. Work gently; if a nut won't budge after a few turns, apply penetrating oil and wait five minutes. Hand-tighten the final turn to avoid stripping.
3. Disconnect the drain and pop-up rod. The drain P-trap unscrews by hand or with an adjustable wrench at the slip nuts. If your faucet has a pop-up stopper, locate the rod extending from the faucet body into the wall behind the sink. This rod typically sits in a clip and pulls straight out. Disconnect it now to free up space.
4. Remove the old faucet. Working underneath the sink, locate the mounting nuts holding the faucet base to the countertop. There are typically two. Use an adjustable wrench or basin wrench (a specialized wrench for tight spaces) to unscrew them counterclockwise. The faucet will now lift away from the countertop. From the top, pull the old faucet straight up and out of the sink opening.
5. Clean the sink opening and install the new faucet. Wipe away old caulk, mineral deposits, and debris from the sink opening with a damp rag. Set the new faucet into place from the top, aligning it so the spout points toward the drain and the handles sit evenly on either side. Thread the mounting bolts from underneath by hand first to ensure they're straight, then tighten them snug with your wrench—firm, not hard enough to flex the faucet.
6. Connect the supply lines and test. Hand-thread the supply line compression nuts onto the faucet inlet ports (hot on the left, cold on the right). Use your wrench to snug them—about a quarter-turn past hand-tight. Do the same with the drain connection. Turn the shutoff valves counterclockwise slowly and fully. Turn on the faucet and check for leaks at all connections for 30 seconds.
7. Reconnect the pop-up and seal. If your faucet has a pop-up stopper, reconnect the rod from the faucet body into the clip behind the sink, then test the stopper handle. Apply a bead of silicone caulk around the base of the faucet where it meets the sink or countertop, smoothing it with a wet finger for a clean appearance. Allow the caulk to cure for two hours before using the sink.
8. Return items under the sink and check once more. After the caulk has fully set, reorganize the space under the sink and return items to their storage spots. Leave the cabinet open for a few hours to check that no leaks have developed. Turn the faucet on and off a few times and run water for 60 seconds to confirm everything is working smoothly.