A jet pump is extremely useful when you need to suction lift water from an underground water body like a well or a deep water tank. These are self-priming pumps. But note that the flow of water there is inversely proportional to the depth of the pump. As the pump goes deeper underground the flow decreases to the destination. Jet pumps are basically centrifugal water pumps that are loaded with a venturi for better performance. These pumps can easily extract water from a depth of 7-9 metres and they are a bit noisy as compared to their counterparts.