Abstract: A pump system includes a displacement pump whose oscillating fluid pressure variations are connected to drive a membrane pump. The membrane pump in turn oscillates fluid in a fluid-filled vertical pipe connected to a fluid-filled commuting pipe. The displacement of fluid in the commuting pipe induces intake of a fluid to be pumped into the commuting pipe during an intake portion of the oscillation and also induces expulsion of the fluid to be pumped during the remaining portion of the oscillation. The commuting pipe is made long enough so that fluid drawn in during the intake portion does not pass into the vertical pipe but stays in the commuting pipe. A heat exchanger about the vertical pipe dissipates heat that may be passed to the fluid therein by conduction or convection.