Abstract: A method for filtering a fluid to obtain a fluid having a known purity is described. The fluid is filtered with a filtration system, and upstream of a final filtration stage of the filtration system, a purity of the fluid is measured. A purity of the fluid filtered by the filtration system is determined by correcting the measured purity with a filtration behavior of the final filtration stage. In an embodiment, the fluid comprises an ultra pure water for use as an immersion liquid in a lithographic apparatus.

Abstract: In a lithographic projection apparatus, there is provided a liquid supply system comprising a container at least partly defining a space between the projection system and the substrate, the container having a selectively openable and closeable aperture therein, and a closure configured to selectively close and open the aperture. In an embodiment, the shutter may comprise a channel in a surface of the shutter facing the aperture and/or the shutter may be displaced from the liquid supply system when connected to the liquid supply system. Further, in a lithographic apparatus, there is provided a liquid supply system configured to provide a liquid, through which the beam is to be projected, in a space between a projection system and a substrate and a controller configured to control application to the projection system of a force related to a weight transfer attributable to a member of the liquid supply system.