A pumping system and a method for pumping liquid from a lower level to an operatively higher level are disclosed. The pumping system includes a pumping device, a bent delivery conduit, a single control port opening and control elements. The conduit has an operatively inclined ascending conduit section; an operatively inclined descending conduit section and an operatively horizontal peak section between the inclined sections; one end of the ascending conduit fitted to the outlet of the pumping device and one end of the descending conduit being below liquid level of the higher level. The single port opening is provided at the junction between the horizontal peak section and the descending conduit section, and spaced apart from the ascending conduit junction. The control elements introduce pressurized air into and evacuate air from the delivery conduit through the single port opening.