Abstract: A filter system is described which comprises a vessel (10) containing a plurality of sets of discs (41). Each set of discs (41) comprises a number of discs (40) stacked one above the other. The discs (40) have grooves (50) on their opposite sides so that media to be filtered passes through the grooves and contaminants in the media are prevented from passing through the grooves or trapped by the grooves. A backwash system (25) is provided for supplying air to force liquid in the opposite direction through the grooves to wash any contaminant out of the grooves. An air vent (26) is provided for allowing compressed air to escape from the vessel (10) and an outlet (16) is provided for discharge of contaminant.