Sewer gas is one of the most unpleasant odors that you can experience. It comes from the sewer lines in your home and is usually kept out by a simple contraption called a p-trap. This is the name for that bend on the pipe that you will find under your sink and on your toilet. Water will stand inside of this bend blocking sewer gas from leaking into your home while still allowing water to flow. Sometimes p-traps will fail, however, and when this happens, you will quickly notice. Why does this happen?
Sometimes it is because of a sink being used infrequently and thus drying out. If that is happening, you can install a tap primer, a device that will add water to the p-trap whenever it is running low.
Overloading a p-trap can also cause it to fail. This is the case when you have more than 2 pipes draining through the same p-trap.