Our place of business has a public bathroom with appr. 10 toilet stalls. We frequently have a problem with a strong smell from the sewer. Is it harmful to breathe? Is this methane gas? What can we do to eliminate it?
You might have to reset one of the bowls, have a Plumber come out and check it out, you can take easter egg dye and put in tank or bowl and flush it down and see if it leaks out at floor, they also have eq. to test for gas.