Fix a Dripping Bathroom Faucet

A dripping bathroom faucet costs you money and peace of mind. That one drop every few seconds adds up to hundreds of gallons a year, and the sound alone is maddening at night. The good news: you don't need a plumber. Nearly every bathroom faucet drips for the same reason—a worn seal inside the valve stem—and the fix is straightforward enough that any homeowner can handle it in less than an hour. The key is identifying which type of faucet you have, because the internal parts differ slightly. Once you know that, you're halfway done.

1. Know Your Faucet Type. Look at the top of your faucet where the handles meet the spout. Single-handle faucets have one lever or knob controlling both hot and cold. Two-handle faucets have separate hot and cold handles, often with a spout in the middle. Three-piece faucets have a separate spout with handles on either side. The drip is usually coming from the spout itself, not the handles. Knowing which type you have tells you which internal cartridge or washer you'll need to replace.
2. Kill the Water Flow. Crouch under the sink and locate the two shutoff valves—one for hot water (usually on the left) and one for cold (usually on the right). They look like small knobs or levers attached to the copper or plastic pipes. Turn each one clockwise (righty-tighty) until they stop. Don't force them; they should turn smoothly. Now turn on the faucet at the sink to release any remaining water pressure. You'll hear air come out. Let it run for a few seconds until nothing comes out.
3. Pop Off the Handle. Look for a small decorative cap or cover on top of the handle. For lever handles, this is usually a thin plastic or metal disc. For knob handles, it's often a small circular cover. Pry it off gently with a flathead screwdriver—you'll see a screw underneath. Remove that screw. The handle will now slide or pull off. If your faucet has two separate handles, you only need to remove the one for the dripping side (usually cold water).
4. Unscrew the Packing Nut. Under the handle you just removed, you'll see a decorative trim ring (a wide, shallow ring). Unscrew it by hand or with an adjustable wrench, turning counterclockwise. Underneath that is the packing nut—a hexagonal nut that holds the cartridge or stem in place. Use your adjustable wrench to turn it counterclockwise until it's loose enough to unscrew by hand. Don't force it; if it's stuck, apply a penetrating oil and wait five minutes.
5. Extract the Worn Part. Once the packing nut is off, you'll see a cylindrical part sticking up—this is either a cartridge (for single-handle faucets) or a stem (for two-handle faucets). Grasp it firmly with pliers and pull straight up. It should come out; don't wiggle it or twist. If it's stuck, spray penetrating oil around the base and wait ten minutes, then try again. You'll now see the inside of the valve body—this is where the old rubber washer or O-rings are.
6. Clean the Valve Seat. Inside the faucet body where the cartridge was sitting, you'll see a small opening. This is the valve seat. Use a flashlight to look inside. If you see mineral deposits (white or greenish crusty buildup), soak a rag in white vinegar and stuff it into the opening for five minutes, then wipe it clean with a dry cloth. If the seat is pitted or rough, you may need to replace it with a seat wrench (this is rare, and you can call a plumber instead if needed).
7. Match the Exact Part. Take your old cartridge or stem to your local hardware or plumbing supply store. Hand it to an associate and say 'I need an exact replacement for this.' Do not guess or buy a 'universal' cartridge—they don't work well. The part costs between $8 and $25. If your faucet is more than ten years old or made by an uncommon brand, call ahead to make sure the store has it in stock.
8. Seat the New Cartridge. Take the new part and insert it straight down into the valve body, aligning any notches or alignment marks. Push it down firmly until you feel it seat. You may need to rotate it slightly to find the right position—there's usually a slot or notch that guides it. Once it's seated, screw the packing nut back on by hand, then tighten it with an adjustable wrench. Don't over-tighten; snug is enough.
9. Reattach the Handle. Screw the trim ring back on by hand, turning clockwise until it's snug. Now position the handle so it points in the 'off' direction (usually straight down or to the side). Slide the handle onto the stem, align the screw hole, and insert the small screw you saved. Tighten it by hand, then add the decorative cap back on top. For two-handle faucets, repeat this for both sides if needed.
10. Restore Water Flow. Reach under the sink and turn both shutoff valves counterclockwise (lefty-loosey) to turn the water back on. Turn them slowly; you don't need to crank hard. Once they're fully open, go back to the sink and turn on the faucet. Let it run for a few seconds to clear any air from the lines. Check both the hot and cold sides, and look under the sink for any leaks around the shutoff valves or connections.
11. Confirm the Fix Works. Watch the faucet over the next day. A good faucet should not drip at all when the handles are in the 'off' position. If it still drips, turn off the water again and check that the packing nut is tight—sometimes it needs another quarter turn. If tightening doesn't help, the new cartridge may be defective. Return it to the store and get a replacement. If water is leaking from under the sink at the shutoff valves or connections, tighten those connections with a wrench.