Tubs typically clog due to a build-up of hair, soap scum or other residue. Most clogs begin slowly, with a tub gradually draining slower day by day. Liquid and homemade drain openers may be used before the clog becomes a major problem, while special drain opening equipment works best when a tub has become fully clogged. Occasionally, the stopper on the drain may become coated with soap scum and prevent the tub from draining. If other methods to open the drain do not work, unscrew the stopper and clean off any soap scum before calling a plumber.
If you want to avoid using a lot of chemicals in your tub drain, homemade drain openers provide the best option. A suggestion from the website Living on a Dime: When you first notice a tub draining slowly, pour 1/2 cup of baking soda down the drain along with 1/2 cup of vinegar to break down some of the soap scum and build-up in the drain. Dissolving 1/2 cup of salt in 2 to 3 cups of boiling water and pouring it down a drain with metal pipes may also work to reduce initial buildup. Rinse the drain with at least a quart of boiling water to remove any loose residue after using either of these treatments.
Chemical drain openers, such as Drano and Liquid-Plumr, are rated highly by customers of hardware, home improvement and large discount stores. These products offer relief for slow-draining tubs and tubs that have become fully clogged, by using chemicals to break down soap scum, hair and other build-up that keeps the tub from draining properly. Some chemical drain openers come in multiple forms. Liquid and foam drain cleaners work best on slow-draining tubs, while gel drain cleaners are designed to break through standing water and attack the clog in a drain.
Special drain opening equipment works best when you want to avoid pouring chemicals or any substances down the drain and for stubborn clogs when other methods have failed. For a slow-draining tub, placing a wet washcloth over the drain and using a plunger on the drain may be enough to remove a clog, Merle Henkenius advises on the This Old House website. A simple bent wire hanger with its end shaped into a hook works best to pull out large clumps of hair. For more stubborn clogs, use a sewer snake or plumber's auger to extend down the pipe and physically break up the clog.