ARS Rescue RooterAir Conditioning, Heating, Indoor Air Quality, Plumbing, Drain Cleaning & Sewer Lines

Could you tell me why one would put a drain connected to the sewer system under the washing machine? To be more specific, I started smelling a sewer smell in the washing machine. After weeks of this I moved the washing machine to discover a hole/drain that was dried up that most likely runs to a sewer line. Thank you.

karen, ogden, UT

Good question. The drain you are describing is called a “floor drain”. In businesses they are utilized in areas that require drainage for fluids that end up on the floor – primarily in restaurants. The design of these drains is simple. If you look under your kitchen sink, you will see a portion of the pipe that resembles the letter “U”, and if you look at it with the pipe that connects to it, it will resemble the letter “P”. That is called the p-trap. The reason for the p-trap is simply to hold water within its bends thus blocking the admittance of sewer gas from the rest of the sewer system. Now imagine that one of these p-traps is installed beneath the pipe you discovered under your washing machine. If it has not had fluids emptied into it for an extended period of time, it will “dry out” thus allowing sewer gas to escape into the air, causing an unpleasant smell. By pouring water in the drain occasionally, you can eliminate the sewer gas surfacing. Why it was installed where it is would depend on the needs of the person who installed it, whether it was installed upon initial construction, or added later. I hope this helps.