A clog in the toilet's drain will cause the bowl to overfill with water since the water that normally would exit the bowl is partly or completely obstructed. Some toilets will not overflow when there is a clog, but others will spill over when there is only a partial clog in the drain.What should you do if your toilet overflows?
If the toilet is overflowing quickly, turn off the water by turning the valve behind the toilet. If you are unable to turn off the water, then open the tank lid, lift the float ball and secure it so that it does not drop to the water. Then turn off the water at the main shutoff.What to do when your toilet is overflowing?
Align the rubber cup of a toilet plunger over the center of the hole of the toilet bowl. Apply downward pressure slowly at first, gradually increasing the speed and intensity. If a clog has caused the overflow, a plunger will dislodge the mass and allow water to escape through the plumbing.