Clearing a clogged drain in a sink, bathtub or toilet is often a fairly simple do-it-yourself project, if the correct approach is used. Following are some tips that can clear up clogs and help prevent them from happening again. But before using any of the tools or techniques described below, I recommend fishing in the drain with a piece of stiff wire, hooked at the end, to pull out wads of hair or other debris that might be causing the clog.
Force cup. This inexpensive tool, also called a plunger or plumber’s friend, is the key to opening many drains. I keep two types on hand: a full-size force cup with a large rubber cup for toilets, tubs and large sinks, and a small one for bathroom sinks. Attempting to use a large force cup in a small sink can send water spewing in all directions.
A fixture should contain several inches of water for a force cup to work properly–run or pour some in if necessary. Another important step in using a force cup is to seal off overflow holes in the fixture. In a sink, these holes can be at the rear or under the rim. In a tub, the overflow is often concealed by a decorative plate or the lever that operates the tub drain.
How to Clear a Clogged Drain
Chemicals. Chemical drain cleaners are useful in some situations, but my personal rule is to never use them unless a drain is at least partially open. The best use of chemical drain cleaners is in maintenance. Occasional use in a troublesome drain can help prevent serious clogs. source