How to Fix a Leaking Sink P-Trap

Plumbing beneath a sink is one of those spaces we usually ignore until it forces us to pay attention with the sound of a steady drip or the musty scent of stagnant water. The P-trap, that U-shaped pipe hanging under your basin, serves a vital purpose by holding a water seal that prevents sewer gases from entering your home. When it starts to leak, it is rarely a sign of a structural failure in your plumbing system; usually, it just means a connection has vibrated loose or a small rubber gasket has given up the ghost. Fixing this is a classic DIY rite of passage that requires almost no specialized equipment. Whether you are dealing with a plastic PVC assembly or an older metal pipe, the logic remains the same. Once you tackle this, you will realize that beneath the vanity, the mechanics are straightforward and forgiving. Keep your bucket handy, work slowly, and you will have your under-sink area bone-dry again in less time than it takes to go to the store.

  1. Protect Your Space First. Remove all cleaning supplies and storage items from under the sink. Place a bucket or a small basin directly beneath the P-trap to catch any residual water once you break the seal.
  2. Break the Seal Gently. Identify the two large plastic or metal nuts holding the P-trap in place. Turn them counter-clockwise by hand, or use channel-lock pliers if they are seized, to loosen them.
  3. Find the Culprit. Slide the trap off the pipe ends and let the trapped water drain into your bucket. Examine the rubber washers inside the connections for cracks, hardening, or debris.
  4. Swap the Worn Seals. Slide the old washers off the pipe ends and discard them. Roll your new tapered washers onto the pipes, ensuring the tapered (beveled) side faces the direction of the connection.
  5. Put It Back Together. Slide the trap back into position, seating it firmly against the pipe ends. Hand-tighten the slip nuts onto the threads until you feel resistance.
  6. Verify the Fix Works. Turn on the faucet and let the water run for two minutes while observing the connections for any sign of moisture. If a bead of water appears, give the nut a quarter-turn more by hand.