Can I fix a leaking faucet myself, or do I need a plumber?

A dripping faucet is usually a worn washer, O-ring, or cartridge — a very common DIY fix with a few dollars in parts. Shut off the supply valves first and take the old cartridge to the store to match it. Call a plumber if the leak is under the sink, at the shutoff, or in the wall, or if the valve won't stop the water.