Why is my bathroom sink clogged or draining slowly?

A clogged bathroom sink usually isn't an emergency. But water coming up in the tub or shower is. That means the main drain is backing up. Stop using water and call a plumber today. Also call if you poured in drain cleaner and the sink's still full. Don't plunge it, Drano's label says.

A slow bathroom sink is most often hair and soap gunk caught on the stopper or just under it. Pull the stopper out and clean it. Home Depot says if the stopper is dirty, the drain probably is too. If the tub and the toilet are slow too, it's the main drain. Call a plumber (This Old House, HomeTips).

You take out a bathroom sink stopper by lifting it, twisting it, or loosening a nut under the sink. Try lifting it first. No luck? Lift and turn it to the left (Home Depot). Still stuck? Look under the sink, behind the drain. A thin rod sticks out the back, held on by a nut. Put a towel down, unscrew the nut by hand, and slide the rod back. Now the stopper lifts out (Moen, Kohler).

A bathroom sink stopper that won't open has usually come loose from the rod under the sink. That rod goes through a flat metal strap with holes, held by a spring clip. If the rod slipped out, push it back through a hole and clip it. Kohler says to move it to a different hole to change how far the stopper opens. If the rod is broken, Moen says to put in a new one.

A bathroom sink that drains slowly with no clog in sight often has a stopper that isn't opening all the way. Lift the knob and watch the stopper. It should pop up clearly. If it doesn't, see the stopper question above. A gunked-up overflow hole can slow it too, because the drain needs air (Bob Vila). Slow drains and gurgling in other spots point to a blocked vent or the main drain. That's a plumber's job (HomeTips).

Baking soda and vinegar rarely clears a clogged bathroom sink. The fizz looks busy, but Poison Control says the gas doesn't build up enough pressure to push a clog out. It's also unlikely to melt a tough clog. Bob Vila says it can help with light buildup, and it won't hurt your pipes. For hair, pulling the stopper and cleaning it is faster and surer.

Boiling water isn't a good way to unclog a bathroom sink, because it can damage plastic pipes. Home Depot says it can hurt porcelain sinks too, and Angi warns about plastic pipes. Hot tap water is fine.

A bathroom sink that gurgles as it drains often has a partial clog. Clean the stopper and the U-shaped pipe first. A gurgle can also mean the pipe that lets your drains breathe is blocked, or the main drain is starting to clog (HomeTips). If the toilet or tub gurgles too, or it keeps going after you clean, call a plumber.

A smelly bathroom sink most often has gunk in the overflow hole or on the stopper. Scrub the overflow with a small brush and hot water (Bob Vila). Clean the stopper too. Sink you hardly use? The water in the U-shaped pipe may have dried up. Pour in about a quart of water (Mr. Rooter). A sewage smell with slow drains elsewhere means the main drain. Call a plumber.

Drano says its Max Gel is safe for bathroom drains, but you have to follow the label exactly. Never plunge during or after using it. Don't mix it with any other cleaner, because the fumes can be dangerous. If the sink's still full afterward, call a plumber. For hair clogs, pulling the stopper is often faster, and it's free.

A plumber charges about $100–$275 to unclog a simple sink clog, HomeGuide says. HomeAdvisor's average for any drain is $246, and Angi says about $250. A main drain clog costs more, about $100–$800. Cleaning the stopper yourself costs nothing.

Call a plumber or a drain cleaning company for a bathroom sink you can't clear. Try the free checks first: clean the stopper, fish out hair, plunge with the overflow plugged, and clean the U-shaped pipe. Renters should call the landlord first. Have a home warranty? Check it first. Several slow drains at once mean the main drain, and that's a plumber's job.