How to Clean Out and Unclog a Bathroom Sink P-Trap

Begin by completely clearing out the cabinet area underneath your bathroom sink. This will give you ample space to work. Place a bucket directly under the P-trap (the U-shaped bend in the pipe) to catch any water and debris that will spill out. Lay down several old towels around the bucket to protect your cabinet floor from any splashes.

Identify the two large slip nuts that connect the P-trap to the drain assembly. One connects to the vertical pipe coming down from the sink (the tailpiece), and the other connects to the horizontal pipe going into the wall (the drain arm). Attempt to loosen both nuts by turning them counter-clockwise by hand. If they are too tight, use a pair of channel-lock pliers or an adjustable wrench. Apply gentle, steady pressure to avoid damaging the plastic nuts or pipes.

With both slip nuts fully loosened, the P-trap can be removed. Carefully wiggle the trap downwards and pull it away from the tailpiece and drain arm. Try to keep it upright as you lower it to minimize spilling, then turn it upside down over the bucket to empty its contents. You will likely see a collection of hair, soap scum, and other gunk come out.

Take the removed P-trap piece to a utility sink, bathtub, or use a garden hose outside for cleaning. Use a stiff, flexible brush, like a bottle brush, to scrub the inside of the pipe. Use hot water and a small amount of dish soap to help break down grease and soap scum. Clean until the inside is completely clear of all visible obstructions. While cleaning, inspect the plastic or rubber washers from the slip nuts. If they are cracked, deformed, or brittle, you should get replacements from a hardware store.

Slide the slip nuts back onto the tailpiece and drain arm, respectively. Position the clean P-trap back into place, aligning it with both pipes. Ensure the slip joint washers are correctly seated inside the nuts, with the tapered side of the washer facing the flared end of the pipe it is sealing against. Begin tightening the nuts by hand, turning them clockwise. Make sure they thread on easily; if you feel resistance, back them off and restart to avoid cross-threading.

Once the slip nuts are hand-tight, use the channel-lock pliers to give each nut a final quarter- to half-turn. This will snug them up and compress the washer to create a watertight seal. Do not over-tighten. Remove the wet towels and place a clean, dry towel or paper towels under the reassembled trap. Turn on the faucet, first with cold water, then hot, and let it run for at least one minute. Closely inspect both slip nut connections for any signs of dripping or moisture. If a leak is present, try tightening the corresponding nut a little bit more. If it persists, you may need to disassemble and check the washer alignment.