Bathtub drains become blocked with hair, soap scum, dirt and other debris, which usually occurs in the middle of a shower or after a bath. When that happens, the drain will slow down or even clog completely. A homeowner can unclog a stopped up or slow running bathtub drain so it drains as it should without the need to call in the professional plumber.
Remove as much water as possible with a plastic glass or other container and dump it into the bucket. Empty the bucket into a working drain.
Remove the stopper, if there is one, or examine the cross hairs of the drain. Unscrew a lift-up stopper directly from the drain. For pop-up stoppers, raise the lever to the open position, then grab the stopper and pull it out of the drain. Remove any hair and other debris found there. Throw whatever you find into the trash can. Do not toss it into the toilet or you will have a clogged toilet later.
Wash the stopper in a bucket of hot soapy water.
Insert the stopper back into the drain, and test the bathtub for drainage by running some water into the tub. If the water does not drain away, remove the stopper and proceed to the next step.
Smear petroleum jelly over the lip of a plunger. Place the plunger over the drain hole so it covers the drain completely. The petroleum jelly helps provide a tight seal.
Cover the air hole in the tub with a wet cloth a length of duct tape.
Fill the tub with hot water so it covers the rubber portion of the plunger. This gives the plunger a tight seal.
Plunge the plunger in quick up and down movements, but do not lift the lip of the plunger off the tub. You'll want to keep a tight seal. Keep plunging for 2 or more minutes.
Lift the plunger and test the drain. If the water drains out, run hot water through the drain for 10 minutes. If the water does not, remove the water from the tub and proceed to the next step.
Remove the overflow plate. The removal process depends on the type of overflow plate you have, but most are removed by taking out the screws.
Insert the snake's head or auger into the drain 3 to 4 inches and then turn the wheel in a clockwise direction until it hits an obstruction.
Reverse the direction by turning the handle in a counterclockwise direction 1 to 2 inches. This brings the auger back toward you.
Reverse the direction again to hit against the clog. Repeat the forward-and-backward motion until you no longer feel the obstruction. Do not try to force the auger through the obstruction all at once or you may push the clog further into the drain.
Remove the auger by turning the handle in a counterclockwise direction.
Wipe the cable off with an old rag as you reel it in to keep the mess minimal. Remove the gunk from the auger head into a bucket. You may have to repeat this action several times until the water flows through the drain easily.
Replace the overflow plate.
Turn on the hot water and allow it to run through the drain for about 10 minutes. This clears out any debris left in the drain.