In the school that I work we have had the smell of sewer gas really bad. They (the big wigs) would say just pour water down the trap. This would work for a while but then it would come back. Only when people started getting sick did they do something. they found the pipe to vent the gaes out of the build had came loose. I would like to know if there is a tester that could of took reads of the type of gas or how high it was. This has been going on for a while.