Abstract: A self-actuating gas/liquid separator which depends on the counterbalancing f the liquid in a closed container in excess of a certain height and the vacuum gas pressure for its actuation and operation. Primarily this invention was directed to the separation of water and methane gas after they are discharged from an inclined coal mine drainage bore hole. Basically, there are two inclined coaxial conduits, one inside the other, with the inner smaller conduit providing the path for the movement of the gas and the outer larger conduit the path for the liquid. Attached to the larger conduit, near its end remote from the source of gas and liquid to be separated, is a third conduit with a U-shaped section and a one-way liquid passing check valve. Liquids drain into the first and third conduits and the second conduit is operably subjected to a vacuum generating source.