The unique design of the in-tank (retractable) pump allows it to be installed inside a storage tank in a vertical pump column with a suction (foot) valve located at the bottom. Because the pump is installed through the top of the tank, all connections below the maximum liquid level of the tank can be eliminated. This design eliminates the possibility of major tank leakage because of a pipe or connection problem, and also permits the storage vessel to be located below ground level.