Fix a Leaking Kitchen or Bathroom Faucet

A dripping faucet is one of those small annoyances that gets worse the longer you ignore it. Beyond the maddening sound, a leak that drips once per second adds up to about 3,000 gallons per year—that's money straight down the drain and a water bill that doesn't deserve to climb. The good news: most faucet leaks are fixable without calling a plumber. The leak usually lives in one of three places—the washers and seats inside a compression faucet, the cartridge or cartridge seals in a single-handle faucet, or the ball assembly in a ball-type faucet. Identifying which kind you have takes 30 seconds. Fixing it takes about an hour, and the parts cost between five and thirty dollars. A faucet that's been dripping for months will feel like it's been running downhill, but once you've replaced the worn piece, it'll run tight and quiet again.

1. Know Your Faucet Type. Look at the handle configuration. If you have two separate handles (hot and cold), it's a compression faucet. If you have a single lever that moves up and down or side to side, it's a single-handle faucet (either cartridge or ball-type). Ball-type faucets have a distinctive rounded cap on top of the spout. Compression faucets are the oldest design and most common in older homes. Single-handle cartridge faucets are what you'll find in most newer kitchens. Write down which type you have—it determines which repair kit you buy.
2. Stop the Water First. Crawl under the sink and locate the shutoff valves on both hot and cold lines. They're usually oval or round knobs near the base of the faucet pipes. Turn them clockwise as far as they'll go. Open the faucet at the sink to confirm the water is off—you should get nothing but air. If there are no shutoff valves under the sink, turn off the main water supply at the meter or entry point to the house.
3. Free the Handle. For compression and cartridge faucets, look for a set screw on or near the handle base—it's often hidden under a decorative cap or button. Pry the cap off gently with a flathead screwdriver, then unscrew the set screw with an Allen wrench or Phillips screwdriver, depending on the faucet design. Lift the handle straight up. For ball-type faucets, look for a small set screw on the side of the handle and loosen it with an Allen wrench, then slide the handle off. Don't force anything—if it feels stuck, apply penetrating oil and wait a few minutes.
4. Loosen the Packing Nut. Once the handle is off, you'll see a decorative trim ring around the faucet body and underneath it, a large hexagonal or round nut called the packing nut. Use an adjustable wrench or faucet removal tool to turn the packing nut counterclockwise. Remove it completely—it may be hand-tight or require steady pressure. Set it aside. For compression faucets, you may see a second decorative ring beneath this that can also be removed.
5. Swap the Washers. With the packing nut removed, you'll see the valve stem sticking up. Turn it counterclockwise with a screwdriver or valve-stem socket until it stops—don't force it. The stem will come out completely. At the bottom of the stem, you'll see a small brass washer held in place by a screw. Unscrew it and replace it with a new washer from your repair kit. Inspect the valve seat (the brass ring inside the faucet body where the washer sits). If it's pitted or corroded, use a seat dresser tool to smooth it, or replace it with a new one if your kit includes it. Reinstall the stem, turning it clockwise until hand-tight.
6. Install New Cartridge. Once the packing nut is removed, you'll see a cartridge (a cylindrical plastic or brass component) sitting in the faucet body. It may have a locking ring or clip around the base. If so, pry it off with a flathead screwdriver. Grab the cartridge with pliers and pull it straight up and out—it should come free with steady pressure. Take it to the hardware store and match it exactly, or bring the faucet model number from under the sink. Install the new cartridge by reversing the process: slide it down into the body, align the hot and cold ports, and secure the locking ring or clip if there is one.
7. Replace Ball Assembly. With the handle off and the packing nut removed, you'll see the faucet cap (a rounded metal collar). Use a faucet cap wrench (or adjustable wrench in a pinch) to turn it counterclockwise and remove it. The ball assembly will be loose underneath. Remove it and the springs and inlet seals below it. These seals are small and easy to lose—have your repair kit handy. Replace both the springs and inlet seals with new ones, and reinstall the ball in the reverse order it came out. Rethread the cap clockwise until snug.
8. Update the Seals. For compression, cartridge, or ball faucets, O-rings (small rubber rings around the stem or cartridge) can also wear out and cause leaks. If you see white or flattened rubber rings as you're working, replace them with new ones from your repair kit. Slide the old one off gently and stretch the new one on in its place. A small amount of plumber's grease on the new O-ring helps it slide into place more easily.
9. Reassemble the Nut. Once you've replaced the internal parts, screw the packing nut back on hand-tight, then use your wrench to tighten it snugly—don't over-tighten or you'll damage the seal. Reinstall any decorative trim rings that were underneath it, turning them clockwise until they sit flush against the faucet body.
10. Reattach the Handle. Slide the handle back onto the faucet stem, aligning it so hot water flows to the left and cold to the right (standard configuration). Insert the set screw through the handle base and thread it into the stem or handle body by hand first, then tighten it with your Allen wrench or screwdriver. Don't overtighten—just enough that the handle doesn't wiggle. If there's a decorative cap, press it back on over the screw.
11. Confirm It Works. Turn the shutoff valves under the sink counterclockwise slowly to restore water pressure. Start with a quarter turn, then check for leaks around the packing nut area and underneath the sink. If everything is dry, open the valve fully. Run water through the faucet and test both hot and cold flows. The faucet should run smoothly without dripping. Let it run for 30 seconds, then turn it off. Wait a minute and look underneath the sink again for any new leaks.
12. Fix Lingering Drips. If the faucet still drips after you've replaced the washers or cartridge, the problem may be a corroded valve seat (compression faucets) or an incorrect cartridge (single-handle faucets). For compression faucets, remove the handle and stem again and use a seat dresser tool to smooth the valve seat, or replace it entirely if it's deeply pitted. For cartridge faucets, double-check that you've installed the right model—take the faucet model number to the store and verify the cartridge before assuming you've got the wrong part. If the leak is around the packing nut itself, remove the handle and tighten the nut a quarter turn more.