Many things can be wrong.
1. Waste system not vented or vent blocked. ( Check to see if vent is block. You can do this buy going up on the roof and looking down the vent pipe. Some times leaves and birds nest can get stuck in vent at roof if so remove blockage.)......
2. If there is a toilet on the second floor on the same waste stack and not vented separately from the toilet on first floor when flush would such the water out of the toilet on the first floor from the momentum (This is if the water is low in the bowl not the tank) Good luck.
Find out more at www.coolplumbingvideos.com
1. Waste system not vented or vent blocked. ( Check to see if vent is block. You can do this buy going up on the roof and looking down the vent pipe. Some times leaves and birds nest can get stuck in vent at roof if so remove blockage.)......
2. If there is a toilet on the second floor on the same waste stack and not vented separately from the toilet on first floor when flush would such the water out of the toilet on the first floor from the momentum (This is if the water is low in the bowl not the tank) Good luck.
Find out more at www.coolplumbingvideos.com
