Interestingly enough, sewage has a fairly distinct smell. Even though it is made of dozens of different components and each household produces different components to make that sewage, it always smells somewhat similar. That means that you can instantly tell sewage when you smell it. A couple of places you might not expect to smell it is in your bathroom or kitchen sink. However, many homeowners know that particular smell. Plumbers say there are several different reasons why this might be the case.