Identify the faucet type: compression, ball, cartridge, or ceramic disc
Shut off the water supply valves under the sink
Cover the drain and open the faucet to relieve pressure
Remove the handle and loosen the packing nut or retaining parts as applicable
Replace worn parts (usually washers, O-rings, seals, or the cartridge)
Inspect the valve seat and clean off mineral buildup
If needed, replace the washer/seal and lightly lubricate with plumber’s grease
Reassemble the faucet in the correct order and tighten securely
Turn the water supply back on and test for leaks
If leaking persists, confirm the correct part was replaced and re-check alignment and seals
For cartridge/ceramic disc faucets, replace the cartridge/disc if the leak continues after seal replacement
If you can’t identify the faucet type or parts, consider replacing the faucet cartridge/assembly or contacting a plumber