An economical ground heat exchanger system uses water-filled membrane liners in cylindrical augured holes. A submersible pump in a drain reservoir is shared by multiple boreholes. Thermal connection with a building or industrial process occurs through a heat exchanger thermally coupled to the reservoir. The pump sends water tempered by the heat exchanger to the water-filled holes, where it exchanges heat with the ground before overflowing through gravity drain piping back to the reservoir for continued recirculation. Heat transfer with the ground occurs through thermal contact between the water, the membrane liners, and earth supporting the liners. Optional raised borehole support rims maintain an “above grade” water level and allow removed soil to be re-used as a berm or planter over manifold pipes that connect the system components, thus eliminating the cost of trenching for the manifold pipes.