An immersion lithographic apparatus is disclosed that includes a detector to measure a distance between a substrate support structure and/or a substrate and a fluid handling system and/or to detect when an item is present between the fluid handling system and a top surface of the substrate and/or substrate support structure. The detector may use information of an electrical property of the fluid provided by the fluid handling system to measure the distance. The detector may measure variation in resistance and/or in capacitance between an electrode of the fluid handling system and an electrode of the substrate and/or substrate support structure.