Leaky Faucet: How to Find the Worn Part and Stop the Drip

A faucet that drips after you shut it off is easy to ignore, but it adds up. The EPA’s WaterSense program estimates that a faucet dripping once per second wastes more than 3,000 gallons a year, and it names worn washers and gaskets as the usual cause. The repair is one of the most approachable plumbing jobs in a house. The only real trick is knowing which kind of faucet you have, because that decides which part wears out.

Identify your faucet type first

Look at the handles and how they move. This tells you what is inside.

What you see	Faucet type	Part that usually fails
Two handles that turn several times and get harder to turn as they close	Compression	Rubber seat washer
One lever that swings left-right and lifts up-down, smooth throughout	Cartridge or ceramic disc	Cartridge or disc seals
One handle on a rounded cap that moves in any direction	Ball	Rubber seats and springs
Two handles that turn only a quarter or half turn	Cartridge (quarter-turn)	Cartridge

If you can find the brand name on the faucet or the box under the sink, write it down. Cartridges are brand and model specific, and taking the old one to the store is the most reliable way to match it.

Diagnose where the water is coming from

1. Drips from the spout with the handle off. The valve is not sealing. Replace the washer (compression) or cartridge (most single-handle faucets).
2. Water pools around the handle or under the lever when the faucet is on. An O-ring around the stem or cartridge has worn. Replace the O-rings.
3. Water collects around the base of the spout on a kitchen faucet. The spout O-rings have failed. They sit where the spout swivels.
4. Water under the sink, not on the counter. This is a supply line or connection leak, not a faucet seal. Tighten or replace the supply line.
5. Only the hot side drips. Hot water wears seals faster. Replace the hot-side washer or cartridge; doing both sides at once is cheap insurance.

Before you start

Shut off the two supply valves under the sink by turning them clockwise. Open the faucet to release pressure and confirm the water is off. Put a rag or the drain stopper in the sink so a small screw cannot disappear down the drain, and lay the parts out in the order you remove them. A photo of each step on your phone makes reassembly simple.

If the valves under the sink will not turn or do not stop the water, shut off the main water supply to the house before going further.

Fix a compression faucet (two handles)

1. Pry off the decorative cap on the handle and remove the screw beneath it. Pull the handle off.
2. Use an adjustable wrench to unscrew the packing nut and pull out the stem.
3. At the bottom of the stem is a rubber washer held by a brass screw. Remove the screw and replace the washer with one of the same size and shape.
4. Look into the faucet body at the brass seat the washer presses against. If it is pitted, a new washer will wear out quickly. A seat wrench removes replaceable seats; a seat dresser smooths fixed ones.
5. Replace the O-ring on the stem while it is out, coat it lightly with plumber’s grease, and reassemble in reverse order.

Fix a cartridge faucet (most single-lever faucets)

1. Remove the handle. The set screw is often hidden under a small cap or on the underside of the lever and may need a hex key.
2. Unscrew the retaining nut or remove the retaining clip that holds the cartridge in place.
3. Note which way the cartridge faces, often marked with a tab or “H” side, then pull it straight up. Stuck cartridges may need a cartridge puller.
4. Install the matching new cartridge in the same orientation. If it goes in rotated, hot and cold will be reversed.
5. Reinstall the clip or nut and the handle, then turn the water back on slowly and check for drips.

For ceramic disc faucets the process is similar, but often only the rubber seals at the bottom of the disc cylinder need replacing. Clean the openings in the faucet body before reinstalling.

Fix a ball faucet

Ball faucets use two small rubber seats with springs under a rotating ball. Repair kits include the seats, springs and cam gasket. Remove the handle and cap, lift out the cam and ball, pull the old seats and springs out with a small screwdriver, and press new ones in. Replace the spout O-rings at the same time, since the spout comes off during this repair.

Common mistakes

• Skipping the shutoff test. Open the faucet after closing the valves to make sure the water really is off.
• Buying a “universal” cartridge without comparing. Similar-looking cartridges can differ in length or spline count.
• Overtightening. Packing nuts and retaining nuts only need to be snug. Crushing a new washer causes the next leak.
• Using petroleum jelly instead of plumber’s grease. It can swell rubber seals.
• Forgetting the aerator. When the water comes back on, unscrew the aerator and flush out any debris loosened by the repair.

When to call a plumber

Call a plumber if the faucet body itself is cracked or corroded, if a seat is damaged and cannot be removed or dressed, if the under-sink shutoff valves are seized or leaking, or if water is getting into the cabinet or wall. At that point a new faucet is often the better value, and older valves may need replacing as well. If you do replace the faucet, the EPA’s WaterSense label identifies models that use less water while meeting performance standards.