Smelly Sink Drain?

“How come my bathroom sink drain smells so bad?”

It’s not always the bathroom sink that smells terrible, it could be any household drain, but more often than not it is the bathroom sink or shower that’s the culprit.

Chrome bathroom drainBathroom sink drain – chrome p-trapThe reason why bathroom drains are more likely to smell is because of the organic matter from our bodies going down the drain, which is the perfect food for bacteria. These bacteria form a slimy residue, called biofilm, along the walls of the pipe, between the trap and the fixture, which in turn helps collect even more organic matter. Since the fixture’s trap forms a water seal that protects against sewer gases escaping, what your smelling is actually the decomposing organic matter on the short vertical section of pipe directly under the sink or the sinks overflow chamber.

How to get rid of the smell

Ok, so now you know why your drain smells like a swamp, but how can you fix it? Below are some common remedies ranging from fairly simple to more involved approaches:

  • If the fixture has a removable trap, place a bucket under it and slowly loosen the threaded connections. Thoroughly clean the trap under hot water with a brush. Use a long flexible brush to clean the remaining vertical pipe that goes up to the sink. Remove any hair that is caught on the strainer.
  • Use a deodorizing enzyme cleaner. These enzyme cleaners can often be purchased at hardware stores and work by attacking the bacteria and masking the odor.
  • Fill the sink with hot water and mix in a generous amount of chlorine bleach, allow to drain and repeat as required. The chlorine will kill the bacteria but may take several cycles.
  • Another way using household items, is to fill your sink with hot water and add equal amounts of baking soda and vinegar (1/2 cup each) and let it drain away.