EE WAS REMOVING HIS 5 GALLON WATER CAN TO ADD ICE. WATER CAN HAD APPROX 2 GALLONS OF WATER IN ITTHE CAN WAS 7FT OFF THE GROUND WHERE HE HAD IT MOUNTED. EE UNSTRAPPED THE CAN & LIFTED IT FROM THE RACK. HE PULLED IT TO HIMSELF, TURNED RIGHT TO LOWER THE CAN DOWN & FELT SHARP PAIN IN LOWER BACK