How Do I Fix a Dripping Faucet?

A dripping faucet is almost always caused by a worn-out internal seal — a cartridge in single-handle faucets, or a rubber washer in older two-handle faucets. The fix takes about 30 minutes, costs under $25 in parts, and stops the drip that can waste over 3,000 gallons of water per year.

Quick diagnosis: what kind of faucet do you have?

One handle (lever or knob controlling both hot and cold)? You have a cartridge faucet. The drip is coming from a worn cartridge — a single replaceable unit.

Two separate handles (one hot, one cold)? You have a compression faucet. The drip is coming from a worn rubber washer or O-ring on the valve stem.

Not sure? Look under the sink at the supply lines, or check the brand name printed on the faucet — you will need it when buying the replacement part.

Tools and parts you will need

• Adjustable wrench and/or basin wrench
• Phillips and flat-head screwdrivers
• Replacement cartridge (single-handle) or washer/O-ring kit (two-handle) — take the old part to the store to match it
• Plumber’s grease (small tube, a few dollars)
• Towel and a small bucket
• Phone camera — take a photo at each disassembly step so reassembly is easy

Fix 1: Single-handle faucet (cartridge replacement)

1. Turn off the water. Close both shut-off valves under the sink (turn clockwise). Open the faucet to release pressure and confirm the water is off.
2. Plug the drain. Drop the stopper in or lay a towel over it — small screws love to disappear down drains.
3. Remove the handle. Look for a small set screw on the side or back of the handle (often hidden under a decorative cap — pry it off gently with a flat screwdriver). Loosen the screw and lift the handle off.
4. Remove the retaining nut and cartridge. Unscrew the dome-shaped retaining nut with your adjustable wrench. Pull the old cartridge straight out. Note its orientation.
5. Install the new cartridge. Apply a thin film of plumber’s grease to the O-rings, slide the new cartridge in exactly the same way the old one sat, and re-tighten the retaining nut — snug, not gorilla-tight.
6. Reassemble and test. Put the handle back on, turn the water supply back on slowly, and check for drips. Run both hot and cold.

Fix 2: Two-handle faucet (washer replacement)

1. Turn off the water at the under-sink shut-off valves and plug the drain.
2. Remove the handle. Pop off the decorative cap (often marked H or C), unscrew the handle screw, and lift the handle off.
3. Unscrew the valve stem. Use your wrench on the packing nut to unscrew the whole stem assembly counter-clockwise.
4. Replace the washer. At the bottom of the stem you will see a small rubber washer held by a brass screw. Remove the screw, swap in the new washer (same size — this is why you brought the old one to the store), and re-tighten the screw.
5. Check the O-ring. While the stem is out, inspect the O-ring around its body. If it is cracked or flattened, replace it too — a five-minute job that prevents future leaks around the handle base.
6. Reassemble and test. Screw the stem back in, reattach the handle, turn the water on, and check for drips.

What the fix costs

A single faucet dripping once per second wastes roughly 3,000 gallons a year — at average US water rates, that is $20–$60 literally down the drain. The $15 part pays for itself fast.

Mistakes to avoid

• Overtightening the retaining nut or stem. This cracks cartridges and deforms new washers. Snug is enough.
• Buying the part before removing the old one. Cartridges are brand- and model-specific. Bring the old cartridge to the store, or order by the exact model number.
• Forgetting which way the cartridge faced. Mark the top with a marker before pulling it out.
• Skipping the plumber’s grease. Dry O-rings tear during installation and leak within weeks.

Preventing future drips

• Do not crank handles shut with force — gentle closing dramatically extends washer life.
• If your water is hard, mineral buildup wears seals faster. Cleaning aerators every few months helps the whole faucet last longer.
• Replace supply-line shut-off valves if they are frozen or corroded while you are under the sink anyway — you will thank yourself next time.

Frequently asked questions

Why does my faucet drip only at night? Thermal expansion. As your water heater runs overnight, pressure in the lines rises slightly and pushes past a worn seal that holds fine during the day. The seal still needs replacing — the nighttime drip is just the early warning.

Can I just tighten the handle harder to stop the drip? Temporarily, maybe. But it grinds the washer down faster and can score the metal valve seat, turning a $5 washer job into a faucet replacement. Fix the seal instead.

My faucet drips from the base of the spout, not the tip. Same fix? Usually yes — that is a worn O-ring on the spout base (common on single-handle kitchen faucets). The cartridge replacement steps above expose it; swap the O-rings while you are in there.

How do I know the valve seat is damaged? If a brand-new washer still drips, run your fingertip around the metal seat inside the faucet body. A rough or grooved seat needs re-seating with a cheap valve-seat wrench, or the faucet needs replacing.

When to call a plumber

• The shut-off valves under the sink are frozen, corroded, or missing — you need a working shut-off before any faucet work.
• Water is leaking inside the wall or under the cabinet floor, not just from the faucet.
• The valve seat is deeply pitted or cracked — re-seating will not save it.
• You have replaced the cartridge or washer correctly and it still drips — the faucet body itself may be worn out.