I saw this question answered in a different thread, but we don't have septic system, we are on public sewar. My wife and I just noticed a sewage smell when we walk in the house. We can't seem to find any source to the smell and it just goes away and then comes back. All the toilets flush fine. I had just unclogged a sink in the master bathroom. Not sure if this has any correlation to the smell. We can't seem to find the issue... help!?

Do you have a sink or any other drain that you seldom use? If the water evaporates from a trap it will allow sewer gasses into your home. How about a floor drain in the garage or the basement?

Pierre--thanks for your quick response. I will check. We notice the smell near the washer/dryer/utility sink, and I noticed it in the basement as well(different floor than the washer/dryer)

I had just fixed a clog in one of our upstairs sinks, so I thought it maybe that, but after doing more research, it doesn't make much sense.