How to Fix a Leaky Faucet

A dripping faucet isn’t just annoying—it can waste thousands of gallons a year and quietly rot the cabinet under your sink. The good news: most leaks come down to a worn rubber part that costs a couple dollars, and you can swap it in an afternoon with tools you probably already own.

What you’ll need

• Adjustable wrench & basin tools — to loosen the packing nut and retainer
• Screwdrivers — Phillips and flathead, for handle screws and set screws
• Slip-joint or channel-lock pliers — for stubborn cartridges and nuts
• Hex/Allen key set — most single-handle faucets hide a set screw under the handle
• Washers & O-rings — the single most common cause of a drip; bring the old one to match size
• Replacement cartridge, stem, or seat — match your faucet type and brand (Moen, Delta, Kohler)
• Plumber’s grease & thread sealant — silicone grease keeps new O-rings supple; tape/dope for threaded joints
• White vinegar or CLR — to dissolve mineral crust on the valve seat
• Rags or a towel — to plug the drain and dry parts as you go

Step 1: Shut off the water and plug the drain

Reach under the sink and turn both supply shut-off valves clockwise until they stop. No under-sink valves? Close the main water valve for the house. Open the faucet to release any pressure and confirm the water is truly off—it should sputter and die.

Do this first, every time: lay a rag over the drain opening. It takes two seconds and it’s the difference between finishing the job and fishing a tiny set screw out of the P-trap.

Step 2: Identify your faucet type

How you fix a leak depends on what’s inside. There are four common designs, and knowing yours saves a wasted trip. Compression faucets have separate hot and cold handles that get harder to turn as you tighten them—these use rubber washers. Cartridge, ball, and ceramic-disc faucets are usually single-handle and rely on a replaceable cartridge or disc assembly.

Step 3: Remove the handle

Pop off the decorative cap on top of the handle (a flathead screwdriver or utility knife works) to expose the screw. Single-handle faucets often use a hidden set screw at the base—that’s where your Allen key set comes in. Back the screw out and lift the handle straight up. If it’s corroded in place, wiggle gently; don’t pry against the finish.

Step 4: Pull the worn part and inspect

Use your wrench to loosen the packing nut or retaining clip, then withdraw the stem or cartridge. This is your moment of truth. On a compression faucet, look at the rubber washer at the bottom of the stem—if it’s cracked, flattened, or grooved, that’s your leak. Check the O-rings around the body too; a drip from the base of the spout (rather than the outlet) almost always means a bad O-ring.

Feel the brass valve seat down inside the faucet body with a fingertip. If it’s pitted or crusty, mineral buildup is chewing up every new washer you install. Soak it with vinegar, scrub it, and dress it with a seat-grinding tool if needed—or replace the seat entirely.

Step 5: Replace parts and reassemble

Take the old part to the store and match it exactly—washers and cartridges are brand- and model-specific, and “close enough” will still drip. Grab the right cartridge or repair kit for your brand. Coat new O-rings with a dab of plumber’s silicone grease so they seat cleanly and last. Reinstall in reverse order: stem or cartridge, packing nut, handle, screw, cap. Snug the nuts firmly but don’t crank—over-tightening splits new washers.

Common mistake: forcing a cartridge in the wrong orientation. Many have a flat side or a notch that must line up with the faucet body, or the hot and cold will be reversed. Match the alignment mark before you seat it home.

Step 6: Turn the water back on and test

Open the shut-off valves slowly—a fast surge can knock a fresh O-ring loose. Run the faucet through hot, cold, and every position, then watch the spout and the base for a full minute. Check under the sink for weeping at the supply connections; a wrap of thread tape usually cures a slow seep there. If it’s bone-dry, you’re done. While you’re under there, a fresh bead of caulk around the faucet base keeps future splashes out of the countertop.

Frequently asked questions

Fixing a drip is one of the most satisfying repairs in the house—small cost, big payoff on your water bill. Match your parts carefully, and if you get stuck or need a washer today, your local independent hardware store can identify the part on sight and hand you the right kit. Questions on your specific faucet? Ask us here.