Abstract: A tubular pump comprises a "tube-within-a-tube" having a lower end adapted to be submerged in a liquid that is under a pressure p.sub.1, for example a pressure of one atmosphere. The inner and outer tubes are in communication with each other adjacent to the submerged lower end. A pneumatic system alternately applies a pressure p.sub.2 lower than the pressure p.sub.1 to both the inner and outer tubes and a pressure p.sub.3 higher than the pressure p.sub.1 to the inner tube. A check valve mounted in the lower end of the outer tube is open when exposed to the pressure p.sub.2 to enable the liquid to flow upward into both tubes to a height h.sub.1 supported by the pressure p.sub.1 and is closed when exposed to the pressure p.sub.3 to prevent the liquid from flowing backward through the check valve. The liquid therefore flows from the inner tube upward through the outer tube in response to the pressure p.sub.3. A sump line is connected to the outer tube at a height h.sub.2 greater than the height h.sub.1.