Hi, I had a kitchen sink blockage that sent drain water into the Dishwasher. While I don't have an air gap, my Diswasher drain hose comes from the disposal and loops up along side the sink(at least 6 inches above the bottom of the sink). The backup occurred while my wife was doing dishes and the level in the sink never exceeded 1 inch. Is there a scenario I am missing that would have put drain water over the loop and into the Dishwasher?