Fix a Leaky Bathroom Faucet

A dripping faucet is one of those problems that seems minor until you realize it's wasting water and money. That steady plink-plink-plink from your sink isn't just annoying—it adds up to thousands of gallons a year. The good news is that fixing it is straightforward. Most leaks are caused by a worn washer, O-ring, or cartridge inside the valve body, and replacing these parts takes basic tools and maybe an hour of your time. You'll need to identify which type of faucet you have, find the right replacement parts, and know where to turn off the water. After that, it's mostly just disassembly, swap, and reassembly.

1. Shut off the water supply. Locate the shut-off valves under the sink—there should be two, one for hot and one for cold. Turn both valves clockwise until they stop. Open the faucet to release any remaining water pressure in the lines. If you can't find or operate the shut-off valves, you'll need to shut off the main water supply to the house.
2. Identify your faucet type and remove the handle. Look for the set screw on the handle—it's usually under a small cap or button near the base. Pry off the cap with a flathead screwdriver if necessary, then unscrew the set screw. Pull the handle straight up and off. If your faucet has a cartridge (single-handle models often do), you'll see it right below the handle. If it has separate hot and cold handles, each one operates a separate valve underneath.
3. Remove the packing nut and stem. Use an adjustable wrench to unscrew the packing nut (the large nut right under where the handle was). Turn it counterclockwise until it's loose. Once the nut is off, pull the stem straight up. It should come out smoothly. If it's stuck, try turning the handle position back and forth while pulling gently.
4. Replace the washer and O-ring. At the bottom of the stem, you'll find a small brass screw holding a washer in place. Remove the screw with a screwdriver and slide off the old washer. Replace it with an identical new one from your washer kit. Also slide the O-ring off the stem—it's the rubber ring just above the washer seat. Slide a new O-ring of the same size onto the stem.
5. For cartridge faucets, replace the cartridge itself. If you have a single-handle faucet and identified a cartridge (a plastic cylinder), pull it straight out. Note any markings or grooves that show its orientation. Take this cartridge to the hardware store to match the exact model. Install the new one in the same orientation, pushing it firmly until it seats fully. You may need to turn it slightly to align the grooves with the body.
6. Reassemble the faucet. Slide the stem back into the valve body and hand-tighten the packing nut. Use the wrench to snug it down—firm but not over-tight. Replace the handle by aligning it with the stem and pushing it down, then install and tighten the set screw. Snap the cap back on if you removed one. Recheck all connections to make sure nothing is loose.
7. Turn the water back on and test. Slowly open both shut-off valves by turning them counterclockwise. Open the faucet in hot and cold positions and let it run for a few seconds to clear air from the lines. Check under the sink for any drips. If water leaks from where the stem enters the body, tighten the packing nut a quarter-turn and test again.