How to Clean Out a Bathroom Sink P-Trap

Begin by completely clearing out the cabinet area beneath the bathroom sink to give yourself ample room to work. Place a bucket directly under the U-shaped bend of the P-trap. This bucket is essential for catching the water and debris that will spill out when you disconnect the trap. For extra protection against splashes, you can lay down a few old towels around the base of the bucket. Finally, put on a pair of waterproof gloves to protect your hands from the dirty water and gunk inside the pipe.

Identify the two large slip nuts that hold the P-trap in place. One nut connects the trap to the sink's vertical tailpiece, and the other connects it to the horizontal pipe going into the wall (the trap arm). Attempt to loosen both nuts by turning them counter-clockwise (lefty-loosey) with your hands. If they are too tight, use a pair of channel-lock pliers. When using pliers on plastic nuts, it's a good practice to wrap a rag around the nut first to prevent the tool's teeth from scarring or damaging the plastic.

Once both slip nuts are sufficiently loosened, they should slide freely on the pipes. Carefully pull the U-shaped trap straight down to detach it from the tailpiece and the trap arm. As you lower it, guide it over the bucket. The water and any loose debris inside the trap will immediately spill out into the bucket. Empty the entire contents of the trap into the bucket.

Take the removed P-trap piece to a utility sink, or use a garden hose outside, to clean it thoroughly. Use a flexible bottle brush to scrub the interior walls of the trap, removing all the built-up hair, soap scum, and gunk. A straightened wire coat hanger with a small hook bent at the end can be very effective for pulling out stubborn clumps of hair. Rinse the trap with hot water until it is completely clean. Before reinstalling, use a rag or the brush to quickly clean the end of the sink's tailpiece and the opening of the wall pipe, removing any accessible debris.

Slide the P-trap back into its original position, aligning it with the tailpiece and the trap arm. Ensure that the plastic or rubber slip joint washers are in place on both pipes. The tapered side of the washer should face the flared end of the connecting pipe to create a proper seal. Thread the slip nuts back on by hand, turning them clockwise. Hand-tightening first prevents cross-threading. Once they are snug, you can use channel-lock pliers to give them a final quarter-turn to secure them. Do not over-tighten.

Keep the bucket and towels in place under the newly reassembled trap. Turn on the hot water at the sink faucet and let it run for at least one full minute. This action will fill the P-trap with water, establishing the water seal that prevents sewer gases from entering the room, and will thoroughly test your connections under pressure. While the water is running, carefully observe and feel around both slip nut connections for any signs of dripping or moisture. If a leak is detected, turn off the water and try tightening the leaking nut slightly. If it persists, you may need to disassemble that joint to check the washer's seating and the pipe alignment. Once you have confirmed there are no leaks, you can remove the bucket and towels and clean up your work area.