How to Fix a Slow Bathroom Sink Drain

Quick Fixes

Before taking anything apart, try the simplest solutions first. Remove the drain stopper and clean off any hair and soap scum — this alone often solves the problem. Use a plastic barbed drain cleaning tool (zip-it strip) by inserting it into the drain and pulling it back out — the barbs catch hair and debris. If the drain is still slow, pour half a cup of baking soda followed by half a cup of vinegar into the drain. Wait 30 minutes, then flush with hot water.

Cleaning the P-Trap

If quick fixes do not restore full drainage, the P-trap (the U-shaped pipe under the sink) is likely clogged with accumulated debris. Place a bucket under the P-trap. Unscrew the slip nuts on both ends of the trap by hand or with channel-lock pliers. Carefully lower the trap and dump out its contents into the bucket. Clean the inside of the trap thoroughly with a bottle brush and hot soapy water. Also check the pipe that goes into the wall (the waste arm) for obstructions by inserting a flashlight and looking for buildup.

Addressing Deeper Clogs

If the drain is still slow after cleaning the trap, the clog is deeper in the waste arm or the branch line inside the wall. Insert a small hand-crank drain snake (25-foot model) into the waste arm opening. Feed the snake into the pipe while turning the handle clockwise. When you feel resistance, continue turning to break through the clog. Retract the snake, cleaning debris from the cable as it comes out. Reassemble the P-trap and test the drain with running water.

Preventing Future Slow Drains

Install a hair-catching drain cover to prevent hair from entering the drain. Clean the drain stopper monthly — pop-up stoppers accumulate hair on the pivot rod mechanism beneath the drain. Once a month, flush the drain with a kettle of boiling water to melt soap scum. Avoid letting excessive toothpaste or soap chunks go down the drain. For households with long-haired members, weekly use of a plastic drain cleaning tool keeps the drain clear with minimal effort and no chemicals.