There are many kinds of faucets, but chances are your leaky fixture is a compression faucet -- and it's a snap to fix.
Step 1: Tighten the nut Remove the faucet handle by unscrewing the screw that attaches it, which is often covered by a decorative cap you'll need to carefully pry off. Using your wrench, try tightening the packing nut, which is the nut at the base of the handle's stem. Some leaks are simply caused by a loose nut.
TIP: Put a rag over the drain to catch any small parts you might drop.
Step 2: Turn off water If tightening the nut doesn't solve the problem, you might have to replace the washer. Locate the shut-off valve for the faucet you are repairing and turn off the water.
TIP: The shut-off valve will most likely be beneath the sink. If not, follow the pipes until you find it. Turn the valve's handle to the right to shut off the water.
Step 3: Empty the faucet Open the faucet by twisting the top of the stem until all remaining water in the pipes flows out.
Step 4: Remove the stem assembly Unscrew the packing nut to remove the entire piece that holds the stem, called the stem assembly.
Step 5: Replace the washer If your faucet has a washer on the bottom of the stem assembly, remove the screw holding it on. Replace the old washer with a new one, then tighten the screw.
TIP: The correct size washer is critical; to be on the safe side, take your old one to the hardware store when buying a new one.
Step 6: Wrap the nut If your faucet doesn't have a washer, wrap the packing nut with string or wicking (available at hardware stores), which will act as a washer. Or put a thin line of plumber's putty around the threads at the bottom of the stem assembly.
Step 7: Reassemble Replace the stem assembly and tighten the packing nut.
Step 8: Turn water on Attach the handle and turn the water back on by reopening the shut-off valve. Enjoy the blessed silence!
FACT: Fixing a leaky faucet can save up to 20 gallons of water a day!