Fix a Slow-Draining Bathroom Sink

A slow-draining bathroom sink is one of those problems that gets worse the longer you ignore it. Water pools around your feet while brushing your teeth, toothpaste and hair collect in standing water, and eventually you're looking at a completely clogged drain. The good news: the blockage is almost always in the first 18 inches of pipe, right where you can reach it. Bathroom sink clogs are different from kitchen clogs—they're almost always hair and soap residue, not grease—which means they're straightforward to clear without calling a plumber. The fix takes 30 minutes and costs almost nothing. Start here before you buy anything.

1. Clean the Hidden Hair Trap. Locate the pivot rod underneath the sink—it connects the stopper handle to the stopper plug itself. Unscrew the nut holding the pivot rod to the drain tailpiece (use a wrench or pliers, turn counterclockwise). Pull the rod straight out. You'll see hair wrapped around it like a nest. Clean everything off with your fingers or an old toothbrush. Rinse the stopper plug under warm water and scrub away soap buildup. Reinsert the pivot rod, hand-tighten the nut, then give it one quarter-turn with your wrench.
2. Test the Quick Fix. Plug the drain, fill the sink halfway with warm water, then unplug and let it drain. If water drains at normal speed now, you're done. If it's still slow, the blockage is deeper in the trap.
3. Block and Fill. If the stopper didn't solve it, you need to plunge. First, plug any overflow hole in the sink basin with a wet cloth or your thumb—this creates the pressure needed for plunging to work. Fill the sink with 4-6 inches of water. Make sure you have enough water to cover the plunger cup completely.
4. Dislodge the Blockage. Position the plunger cup directly over the drain hole, pressing down firmly to create a seal. Push down and pull up rapidly 15-20 times in succession without breaking the seal. On the final push, pull the plunger away quickly to break the seal and see if water drains. Repeat if necessary. You should feel resistance for the first few strokes, then a sudden give when the clog breaks free.
5. Verify the Result. Let the water drain completely. If it's still slow, plunge again. Most bathroom sink clogs clear after 2-3 plunging rounds. If water still isn't moving freely, the blockage is in the trap itself or beyond reach of the plunger.
6. Access the Trap. Look under the sink. You'll see a curved pipe section (the trap or P-trap) that looks like the letter P or S. This is where hair and soap accumulate. Place a bucket or old towel directly under the trap to catch water spillage. The trap contains standing water as a safety seal, so expect a small amount of water to come out when you open it.
7. Disconnect the Trap. Using your adjustable wrench, unscrew the large nuts on both ends of the trap (top connection to the sink tailpiece, bottom connection to the wall drainpipe). Turn counterclockwise. Once both nuts are loose, twist the trap by hand to break any mineral buildup seal, then carefully lower it into your bucket. Empty the contents into the bucket. The trap itself will likely contain a dense mass of hair and soap—this is what you're removing.
8. Flush Out the Blockage. Empty the trap completely into the bucket. Rinse it out with hot water from a hose or faucet. Use a bottle brush, old toothbrush, or a straightened wire coat hanger to scrub the interior walls and remove any remaining buildup. Run water through it several times until it's clean and water flows through freely.
9. Probe Beyond the Trap. While the trap is out, look at the two pipes the trap was connected to. Use a plumbing snake or stiff wire to probe up into the sink tailpiece (the pipe coming down from the sink) about 12 inches. Twist and push to dislodge any hair clinging to the walls. Do the same for the wall drain line going back into the wall. This removes secondary blockages that the trap alone won't catch.
10. Reconnect the Trap. Slide the trap back into position, aligning the top and bottom connections. Hand-tighten both nuts first, then use your wrench to snug them another quarter-turn clockwise. Tighten firmly but don't use full force—these plastic nuts crack easily. The trap should sit level and not twist.
11. Check for Leaks. Turn on the faucet and let water run for 30 seconds while watching underneath the sink. Look for water dripping from the trap connections. If you see drops, turn off the water and tighten the leaking nut another quarter-turn. If water runs steady during drainage without leaking, you're good. Now test the sink—water should drain quickly and completely.
12. Restore the Stopper. If you removed the pivot rod earlier, reinsert it now and hand-tighten the nut. Test the stopper handle to make sure it pulls up and pushes down smoothly. The stopper should seal the drain when pushed down.