Where Drain Cleaner Works

• Drain cleaner works best in clogs that reside in the trap, or just above the trap on the drain opening side of the pipe. Drain cleaner is heavier than water, so it falls down the drain and settles at the site of the clog. Chemicals in the cleaner then react with the water to heat up the clog and break down the clog, opening the drain.
  
  

Where Drain Cleaner Does Not Work

• Drain cleaner does not work on clogs that the drain cleaner cannot reach. Any clogs that are in the drain pipe between the drain trap and the sewer line aren't reached by the drain cleaner. The cleaner will simply settle in the trap and remain there. If the drain is clogged only partly, and some water is escaping in to the sewer, some of the drain cleaner may reach the clog, but this is unlikely to be sufficient to break it up and open the drain.
  
  

Plunge

• Attempt to plunge the drain before you do anything else. The caustic chemicals in drain cleaner can wreak havoc on your pipes, and you won't be able to use a plunger safely after you dump them in your drain. Use a plunger on your drain and see if any debris floats up from the clog, or if the water level begins to fall, indicating the drain has opened up.
  
  

Snake

• The next step in freeing up a clog that lies beyond the trap is to use a plumber's "snake." A plumber's snake is a long piece of metal cable or flat steel that is pushed through a drain and used to force clogs down the drain. These can be rented or purchased from most any hardware or home improvement store, and are a way to save a buck busting minor drain clogs, do it yourself style.