you have a blockage past the junction of the drain and the disposer hookup. try removing the trap and see if it is causing the blockage. Have a large bucket or pan under the trap priior to removal to catch any spillage. clog is probably in the trap, but could be past the trap requiring a snake or a waste-king whick hooks to the end of the garden hose and is inserted into the drain line. water preasure will then force the material down the drainline.