Because some water pumps are specifically designed to only work underwater, they are often built with “dry run protection” to protect the pump. Out of water a variety of things can go wrong. The water is often used as a type of lubrication within the pump, without which the pump bearings or gears can be worn away more easily. Another common problem is that because these pumps are built to run underwater, running them out of water will allow the pump to run faster than normal because it will be pushing air instead of water. The speeding up will cause the motor to draw more power which can often damage circuitry or burn something inside the pump from the increased power draw and heat. To prevent this many pumps have circuits inside designed to limit the maximum amount of power that is drawn to match the maximum amount of power needed while running underwater (through testing). This ensures that when the pump is removed from water, it will be able to tell very quickly and shut itself off before it becomes damaged.