A lithographic apparatus includes a substrate table to hold a substrate and a projection system to project a patterned radiation beam onto a target portion of the substrate. A liquid supply system at least partly fills a space between the projection system and the substrate with a liquid, and has a liquid confinement structure to at least partly confine the liquid within the space. An outlet removes a mixture of liquid and gas passing through a gap between the liquid confinement structure and the substrate. An evacuation system draws the mixture through the outlet, and includes a separator tank to separate liquid from gas in the mixture and a separator tank pressure controller, connected to a non-liquid-filled region of the separator tank, to maintain a stable pressure within the non-liquid-filled region.