Washer faucets work with a rubber washer that closes onto a metal washer seat. When the unit hardens or wears out, it causes a leak. You can close the faucet tighter to stop the leaking temporarily but doing so risks further damage to the faucet. Leaky faucets are annoying. You don't need a plumber to make it stop. Follow these simple steps to fix a leak in a washer-type faucet.
Step 1 - Turn Off the Water
Turn off the water at local the valve, if applicable. If not, turn it off at the main valve in the basement, utility room, or crawlspace. Turn off the hot water supply as well.
Step 2 - Take the Faucet Apart
Remove the handle and loosen the screw, which is located beneath a decorative cap at the center of the handle. The cap either unscrews or snaps off when you pry it with a knife blade.
After removing the screw, pry the handle from the stem and remove the packing nut. Once that is done, the entire stem will be exposed. Twist the stem to thread it out. To avoid damaging the faucet with a wrench or pliers, pad the area with electrical tape or a cloth.
Step 3 - Examine the Stem
If the stem is simply dirty, you can clean it and reuse it. If the threads are badly corroded or worn, then you must replace the stem. Take it your local hardware store to find one that matches.
Step 4 - Check the Washer
A brass screw holds the washer in place on the lower end of the stem. Replace the washer if it is worn out or misshapen. Doing so should stop the drip. To get an exact match, take the old washer with you to the store. If the brass screw is damaged, replace it with a new piece.
Step 5 - Inspect the Washer Seat
If you find that you are constantly changing the washer, chances are that the faucet has a damaged seat. The washer seat is located inside the faucet body. The seat should either be refaced with a seat-dressing tool or replaced.
Step 6 - Replace the Washer Seat
If the faucet has a square or hexagonal hole through its center, or if it is slotted for a screwdriver, then the washer seat can be replaced. If upon examination you see that the seat simply has a round hole through its center without any slots, it is not replaceable.
Using a faucet seat wrench, turn the washer seat counterclockwise to loosen it. Apply silicone rubber sealant (RTV) or pipe joint compound around the threads of the seat before you install it. Doing so makes it easier to remove for future repairs.
Step 7 - Reface Washer Seat
If your washer seat cannot be replaced, then you must reface it with a seat-dressing tool. Use the tool according to the manufacturer's directions, placing it in the faucet along with the packing nut. Rotate it until the seat is smooth.
Step 8 - Put Everything Back Together
Replace the parts in the reverse order you took them apart. Apply lubricant to the threads of the stem.
Step 9 - Faucet Leaks Around the Stem
Install new packing to repair leaks around the stem. Nylon-covered or graphite-impregnated packings make a great choice. Their lubrication allows the faucet handle to turn more freely.
Wrap a single turn of this packing around the stem, just beneath the packing nut. Use 3 complete wraps if you're applying string-type packing. If your stem uses O-rings, then replace it. Hand tighten the packing nut, then tighten it another half-turn.
Courtesy of National Retail Hardware Association