How to Repair a Leaky P-Trap

P-traps are the unsung heroes of your home's plumbing, holding a small pool of water to block sewer gases from creeping into your living space. When they fail, it is usually because the seals have dried out or the plastic has developed a hairline fracture, leading to that telltale drip beneath your bathroom or kitchen sink. The repair is straightforward, requiring no specialized training or heavy equipment, just a bit of patience and a steady hand. Done well, a P-trap replacement is a permanent fix that clears up leaks and ensures proper drainage for years. The secret lies in not over-tightening the plastic connections, which can crack the new fittings before they even see a drop of water. You are looking for a clean, drip-free connection that can be disassembled again in the future without the need for a pipe wrench.

Contain the Spillage First. Empty everything from the cabinet and place a shallow bucket or large bowl directly under the P-trap. The trap contains standing water that will spill out as soon as you loosen the nuts.
Free the Stubborn Nuts. Use your hands to turn the plastic slip nuts on both ends of the P-trap counter-clockwise. If they are seized, use channel-lock pliers gently to provide extra leverage, but be careful not to crack the pipe.
Inspect Before You Toss. Pull the P-trap off the tailpiece and the wall pipe. Inspect the washers inside the connections; if they are cracked or compressed, they are likely the source of your leak.
Orient Washers Correctly. Slide the new slip nuts and tapered washers onto the tailpiece and the wall pipe. Ensure the tapered side of the washer faces the direction of the joint it will seal.
Fit and Align the Trap. Position the new P-trap and slide the slip nuts up to engage the threads. Align the pipes so they sit straight and flush to prevent binding.
Verify Your Seal. Hand-tighten all slip nuts until they are snug. Run water into the sink for one minute while observing the joints with a dry paper towel to check for any slow leaks.