Chemical drain cleaners are among the most dangerous cleaning products. Most conventional drain cleaners contain corrosive ingredients like lye and bleach that can severely burn your eyes and skin; some contain dangerous acids. Hundreds of people are seriously injured every year by drain cleaners. You don't need these extremely hazardous products to clear your drains; there is no reason to have them in your home. (If you do, you can dispose of them at one of the Household Chemical Collection events held by the Pennsylvania Resources Council.)
To keep your drains clear, prevention is important. My bathtub drains are prone to frequent clogging. However, I can keep them running freely for a long time if I am diligent about some preventative measures.
Every week or so I pour a cup of baking soda down the drain, and then a few cups of boiling water. I follow that with a cup of white vinegar. This bubbles up in a fun way, usually dislodging yucky black bits. I sometimes then use a plunger to dislodge more gunk.
I have also used natural enzyme drain cleaners, such as CitraDrain, for maintenance. These are easy to use and are effective as a preventative measure. However, I find they don't work any better than the baking soda and vinegar method, and they cost a lot more.
If, as sometimes happens, I fail to keep up with the above measures, after a couple of months my bathtub will begin to drain very slowly, backing up water into the tub. In that case, it is time to reach for our plumber's snake. We have a hand-operated one that is 100 percent effective at cleaning out our sink and tub drains. It cost about $15 at the hardware store. (There are motorized models, but these can be dangerous.)
You won't have to call a plumber for a run-of-the-mill clogged drain if you get and learn how to use a snake.