How to Repair a Leaking Sink Trap

P-traps are the unsung heroes of your home's plumbing, holding a small amount of water to block sewer gases from creeping into your living space. When they start to leak, it is rarely a catastrophic failure of the pipe itself; usually, it is just a hardened washer or a loose slip nut that has finally given up the fight. Catching this early prevents cabinet water damage and keeps your under-sink storage dry. Repairing this is a classic weekend win that requires more patience than raw strength. You are essentially dismantling a puzzle, replacing the small gaskets that create the watertight seal, and putting it back together. Done well, your sink will be drip-free and the connections will be secure enough to withstand the vibration of daily use without weeping a single drop.

1. Clear the Cabinet First. Empty everything from underneath the sink and place a bucket or deep pan directly under the U-bend. Lay down an old towel to soak up any surprise drips during disassembly.
2. Unscrew the Slip Nuts. Use your hands to turn the plastic slip nuts counter-clockwise. If they are seized, use channel-lock pliers very gently to avoid cracking the plastic threads.
3. Extract the P-Trap. Slide the trap out from the wall arm and the tailpiece connected to the sink drain. Empty the trapped water into your bucket immediately.
4. Check for Damage and Debris. Check the threads on the pipes for cracks and scrub away any mineral buildup or debris with a nylon brush. Remove the old rubber washers from the slip joints.
5. Install Fresh Washers. Slide new slip nuts and tapered washers onto the pipes, ensuring the tapered side of the washer faces the direction of the joint connection. This is the seal that stops the water.
6. Reassemble and Check for Leaks. Push the trap back into place and hand-tighten the slip nuts firmly. Turn on the faucet and run water for at least two minutes, checking the connections with a dry paper towel for any moisture.