We recently hooked up to public sewer. Since then we are getting an awful sewer gas smell intermittently. We are at the end of the gravity fed section and from our house on they are a force fed system where it comes into the line by our house with pressure. I have located the smell coming out one of the roof vents on the house. My thoughts are the gas is being pushed through the pipes as it comes from the next town to the gravity fed pipe. Our house the first on the line is getting the sewer gas back up our pipes and since we have traps in the lines it is going up our roof vent and not in the house. How do we stop it from coming up our pipe and out the roof vent? This is very embarrassing especially when we have people at our house every week for Prayer meeting for the new church we are involved with. Please Help!!!!