I ve read through other threads in this regard and I dont know if the problem is similar, the bad odour is coming from downstairs toilet for the last 2 weeks or so but now its so unbearable. The water level in the toilet seems fine to me and there is nothing physical to suggest where the problem is coming from. I was so worried last night I couldnt sleep. Any advice will be highly appreciated. Somebody suggest that I should get a toilet plug hole unblocker but which one? please help.