I live in a old house. Lately , when I take a shower or fill my kitchen sink up to wash dishes and then pour the water out. I get a sewage smell that comes up through my heating vents. I have check the basement to see if there is any water backing up. There is not any. What can I do.. I live in the city.

Its quite possible that your sewer is baking up. When was the last time you had a root-rooter type drain service over to clean-out your main line? I have a really old house, and my neighbor has a really old silver maple. I have to clean my sewer at least once each year. Do you have a floor drain? If so, try filling up your tub a bit and listen at the floor drain when you drain your tub. Gurgling sounds, and extra stink, can be a sign your sewer is not flowing properly. Let me know if this was helpful.

Do you have a basement floor drain? If so fill the trap with Anti-Freeze or cooking oil and see if stinky goesbye-bye. Good luck, Tom