How to Fix a Leaky Pipe Under Your Kitchen Sink

Most sink pipe leaks come from loose connections or worn washers that you can tighten or replace in under an hour with basic tools.

1. Cut Off the Water First. Locate the shut-off valves under the sink and turn them clockwise until tight. If there are no valves under the sink, you'll need to shut off the main water supply to your home. Turn on the faucet to drain any remaining water from the lines.
2. Locate Where Water Escapes. Use a flashlight to examine all visible pipes and connections. Look for water drips, mineral deposits, or wet spots. The leak is usually at a joint where two pipes connect, at the P-trap, or where supply lines connect to shut-off valves.
3. Snug Up the Connections. Use an adjustable wrench to gently tighten any loose nuts or compression fittings. Turn clockwise, but don't overtighten as this can crack fittings or damage threads. Check if this stops the leak before moving to the next step.
4. Swap Out the Seals. If tightening doesn't work, disconnect the leaking joint by turning the nut counterclockwise. Remove the old washer or O-ring and take it to the hardware store for an exact match. Clean the threads, install the new washer, and reconnect the joint hand-tight plus a quarter turn with your wrench.
5. Swap the Bend Pipe. For leaks in the curved P-trap itself, you'll need to replace the entire assembly. Unscrew the slip nuts on both ends, remove the old trap, and install a new one. Make sure the washers are properly seated before tightening the connections.
6. Confirm the Leak Stops. Turn the water supply back on and run the faucet for several minutes. Check all connections you worked on for any new leaks. If you see drips, turn off the water and slightly tighten the connection that's leaking.