1957 house, we have been living for 4 months. In the past week the floor drain in our utility room has intermittently been emitting a sewer smell. I have looked around for causes so far I have:
1) Poured (gallons) water into the drain to ensure it is not dry and not blocked/backed up.
2) Gone up to the vent on the roof to check for obstruction - none visible
Shortly after we moved in I had the main drain inspected by video, saw with my own eyes that everything was in great shape down there - so this combined with 1) makes me think a backup is not the issue.
The smell from the drain has more or less coincided with the spring thaw (Toronto), of what has been a colder than average winter and one with a good amount of snow accumulation. Most of the snow is now melted.
Looking in the drain I can appear to see the top of the opening where the water flows out, this suggests that there is a pathway for the sewer gas to escape. To test this I put a round piece of rubber in the drain so that it is still functional but so that it covers the gap between the water level and the top of the opening. This seemed to do the trick.
My concern is that why is this happening now - I am assuming that the opening has been there the whole time and something has caused the smell to reach the house. Could it be that the thaw has risen the level in the city drains and pushed the gases to the drain?
I want to be sure that I am treating the cause and not just the symptom of a bigger problem. Grateful for any thoughts/experience.