Abstract: Liquid is pumped from a relatively small submerged tank in pumping cycles by discharging a gas at relatively high pressure from a relatively large tank into the submerged tank. When the submerged tank is emptied of liquid, the high pressure gas which fills it is reclaimed by exhausting the same into a second relatively large tank maintained at low pressure. Gas is reclaimed into the second large tank after the next and each subsequent pumping cycle until the resulting pressure differential impedes further transfer. Tanks filled with reclaimed gas are connected to the inlet of the air compressor to reduce the pressure thereacross and lessen the power required to compress the gas required for the pumping.