How to Unclog a Slow-Draining Bathroom Sink

A slow-draining bathroom sink is one of those problems that starts small and gets worse every week until you're standing in a pool of water while brushing your teeth. The culprit is almost always hair tangled with soap residue and mineral deposits, collecting just below the stopper or in the curved trap underneath the sink. The good news: you can fix this yourself in under an hour without chemicals or a plumber's truck. The key is knowing where the clog actually lives—sometimes it's in the overflow hole nobody thinks about, sometimes it's in the pop-up stopper mechanism itself, and sometimes it's deeper in the trap. This guide walks you through each approach, starting with the fastest methods and moving to the ones that work when the others don't.

1. See What You're Up Against. Fill the sink with a few inches of water and watch how it drains. If it disappears completely but slowly, you have a partial clog. If water pools and barely moves, the clog is severe. While the sink is empty, shine a flashlight into the drain opening and look for visible hair wrapped around the stopper post or sitting just inside the drain. Sometimes you can see the entire clog from above.
2. Pull Out the Stopper. Most bathroom sinks have either a pop-up stopper or a lift-and-turn stopper. For pop-up: locate the stopper rod that connects to the overflow pipe under the sink, unscrew the nut holding the rod to the drain assembly, and pull the rod up and out. The stopper will come with it. For lift-and-turn: simply unscrew the stopper clockwise by hand. Examine both the stopper and the rod for hair wrapped around them—you'll almost always find a significant tangle here.
3. Fish Out the Clog. Pull out any visible hair and buildup from the stopper post opening and the horizontal overflow pipe. Use your fingers, needle-nose pliers, or an old toothbrush to dislodge packed hair. The overflow hole (the small opening on the side of the sink bowl) often traps hair too—poke a straightened wire coat hanger through it to break up the clog. Work patiently; a lot of the blockage is sticky buildup, not solid obstruction.
4. Put It Back Together. Feed the stopper rod back through the overflow pipe and the drain assembly. Secure it with the retaining nut underneath the sink, tightening by hand until snug (not cranked tight—you'll crack the fitting). Make sure the stopper moves freely up and down. Screw the stopper itself back into the post if it's the turn-style type.
5. Check for Success. Fill the sink with water and pull the stopper up. The water should flow freely down the drain now. If it still drains slowly, the clog is deeper in the trap or supply line—move to plunging or snaking.
6. Blast It Free. Fill the sink halfway with water. Plug the overflow hole with your hand (or a wet cloth) to seal the system. Place a cup plunger directly over the drain opening and pump vigorously for 15 to 20 strokes. You're trying to create suction that pulls the clog up toward the drain opening. Release and check if water drains. Repeat 2 to 3 times if the first attempt doesn't work.
7. Bore Through the Blockage. If plunging doesn't work, you need a hand-crank drain snake (also called a plumbing auger). These are cheap and sold at every hardware store. Feed the snake's tip into the drain and turn the crank clockwise while gently pushing forward. You'll feel resistance when you hit the clog. Continue cranking and pushing; the snake will break apart hair and debris or pull it back toward the drain opening. When you feel the clog break, crank a few more times, then reverse direction and pull the snake out slowly.
8. Wash Away the Debris. After snaking, run hot water (not boiling—you'll damage the fitting) down the drain for 30 seconds to flush away loosened debris. If you removed the stopper rod, run water with the opening exposed so nothing catches. You should see the water disappear quickly now.
9. Spot Any New Leaks. With the drain running, look underneath the sink at all the connections where you removed or loosened anything. If you see drips at the stopper rod nut or the trap connection, tighten that fitting a quarter turn with a wrench. Do not over-tighten—these fittings are plastic or soft metal and crack easily.