Armed with some basic knowledge and the right tools, drain cleaning is a simple enough job to tackle. Keep in mind that not all drains are created equal; if you find you're having an unusually hard time getting to the clog that is stopping up your drainage system, it's probably time to call in the pros!
Chemical drain cleaners: Just say no!
You turn on the bathroom tap to brush your teeth and are dismayed to see water filling your basin apparently of it's own accord. Your first thought is most likely to grab the a chemical cleaner to unclog your pipes. But, don't do it! Chemical cleaners have, well, chemicals in them that react with the metals and plastics in most drainage systems that create heat and cause damage. It's almost always better to start off with a plunger when facing a clog. Remember, the simplest remedy is often best.
3-step drain cleaning: The basics
Keep in mind that all of the steps listed below are for clearing and cleaning a bathroom sink drain; kitchen sink drains require a different and slightly more complex method.
Step 1: Block the overflow passage and remove the stopper. Most bathroom sinks have either a small hole or a series of holes near the top of the basin, below the tap. This is your overflow passage; you'll need to block this to prevent backflow. Use an old rag or towel to do this. After you've blocked the overflow, remove the stopper.
Step 2: Remove and clean the trap. The trap is the elbow-shaped fitting that is directly beneath your sink. Place a bucket or other container underneath it to catch water. There should be two slip nuts on both ends of the trap that are easily visible; remove them. You can use a snake to clean out any compacted debris.
Step 3: Snake your waste line. If removing the trap doesn't solve the problem, you'll need to auger your waste line to dislodge any substances that may be in your sanitation tee (an area of piping behind your wall). Since your trap is already removed, you can stick a snake directly into your drain and work it around until you knock the blockage loose.
If you try all of the above steps and still have no luck, consider calling in a licensed plumber in the Atlanta area; there are plenty on Kudzu waiting to help solve your drain issues.