Good Morning,

I leave in a brownstone in NYC so the sewer is part of the city sewer system. For the past year at various time I smell sewer like odors on my first floor hallway and upstairs entrance. Both area of above the sewer line pipes that go out of my building. Also at times when I use the bathroom on my lower lever I can smell the odor from the toilet upstairs on the first floor.

When I go to the basement, I can never smell the odors, it that because they rise? Is odor or gases? Is there anything I can put in my toilet to help clean out the sewer system or does this need to be professionally done. We don't smell the odors all the times just once in a while and almost every time it rains.

The toilet it self holds water so to trap gases from comeing into the room.I had a homeowner with a toilet in the basement but never used it and the water dried up causeing gas fumes to come in. when toilets are installed they are placed on a wax that seals between the toilet and the sewer pipe. If the seal is not installed right or worn or mis alighned from toilet shifting. Smells could come from under toilet area.All sinks,toilets,any drain has traps to prevent gases. The vent pipe that travels up and out roof to vent smell and help flow of water may be clogged or may have been cut during renavation. Hope this helps