How to Fix a Leaking Sink P-Trap in 15 Minutes

Why Your P-Trap is Leaking (and How to Fix It)

The P-trap is the curved pipe beneath your kitchen or bathroom sink. Its job is to hold a small amount of water to block sewer gases from entering your home. Because it is constantly under pressure from draining water and subject to temperature shifts, the connections can loosen or degrade over time, leading to a puddle in your cabinet. Fortunately, fixing a leaking P-trap is a straightforward DIY task that requires zero plumbing experience and can be completed in just 15 minutes.

Tools and Materials Needed

• A small bucket or shallow bin (to catch water)
• Old towels or rags
• Channel-lock pliers (only if the slip nuts are too tight for hand-turning)
• Replacement slip-joint washers (usually 1-1/4 inch for bathrooms, 1-1/2 inch for kitchens)

Step 1: Prep Your Workspace and Locate the Leak

Clear out everything under the sink to give yourself room to work. Place a dry towel on the cabinet floor, and position your bucket directly beneath the curved P-trap. Run the sink faucet to pinpoint exactly where the water is dripping. Leaks almost always occur at one of the two threaded connections (slip nuts) on either side of the curved "U" bend.

Step 2: Try Tightening the Slip Nuts First

In many cases, the leak is caused by a slip nut that has vibrated loose over time. Try tightening the leaking nut by hand. Turn it clockwise (righty-tighty). If it is too slippery or stubborn, use channel-lock pliers to gently snug it up—but do not overtighten, especially on plastic pipes, as this can crack the plastic or strip the threads. Wipe the pipe dry and run the faucet again. If the drip stops, you are done!

Step 3: Disassemble the P-Trap

If tightening the nut didn't stop the leak, the internal washer is likely worn out or misaligned. Unscrew the slip nuts on both sides of the curved trap piece. Keep your bucket directly underneath, as the trap is filled with standing water. Once the nuts are fully unscrewed, gently pull the curved trap straight down to remove it, and empty the water into the bucket.

Step 4: Clean the Connections and Replace the Washers

Slide the old plastic slip nuts and rubber or plastic washers off the pipe ends. Use a damp rag to clean any grime, mineral buildup, or old plumbing tape off the threads of the pipes. Inspect the old washers; if they are stiff, cracked, or misshapen, they must be replaced. Slide a new slip nut onto the pipe first, followed by the new wedge-shaped slip-joint washer. Crucial Tip: Always point the thick end of the wedge-shaped washer toward the slip nut, and the thin, tapered end pointing down into the joint where the pipes connect.

Step 5: Reassemble and Test Your Repair

Align the curved P-trap back into position. Hand-tighten the slip nuts onto the threads. Once they are hand-tight, give them an extra quarter-turn with your pliers to ensure a snug seal. Turn on the sink faucet completely and let it run for a full minute while watching the joints. Touch the connections with a dry finger to feel for any trace of moisture. If it remains completely dry, your P-trap is successfully sealed!