Abstract: In a separator for oil and water, successive separating stages are located within concentric chambers in a vertical cylindrical container, each chamber having at its upper end a collecting zone for separated oil, and the stages comprise respectively a first stage incorporating a plurality of concentric annular shells of which at least portions are inclined to the vertical and which are located within an open-ended annular chamber through which liquid flows in an upward direction, a second stage comprising a coagulator through which liquid from the first stage is directed upwardly, and a third stage comprising a filter housed within a cylindrical screen located above the coagulator.