Hello all. I am getting a sewage like smell that is in one upstairs room only. That room has a wall that the sewage pipes exit the upstairs to downstairs. I looked at the pipes in the basement and they are not leaking. I also noticed the smell under our kitchen sinks and seems to be coming from the same wall as upstairs (the sink drains into that wall where the pipes are).

It is not a 100 percent sewage but at times it does smell like poop. Could it be coming from the garbage disposal under the kitchen sink? No other place in the house smells.