An apparatus for filtering a fluid for an irrigation emitter comprising: a) an irrigation outlet [226]； b) a purge outlet [209]； c) an inlet conduit [204] connectable with a fluid source； d) a cavity [216] having at least three openings, a first opening to said irrigation outlet [226], a second opening to said purge outlet [209] and a third opening to said inlet conduit [204], and e) a rotary element [218] having at least two slits [212, 228], said rotary element configured to switch between an operating position and a purge position when rotating within said cavity [216] to align at least one of said two slits [212, 228] with at least one of said three openings； said rotary element includes a filtration slit [212] and said filtration slit [212] is movable when said rotary element [218] rotates between: i) said operative position in which substantially all the fluid flowing within the apparatus is directed through said filtration slit [212] and out to the irrigation outlet [226] and ii) a purge position in which the direction of flow through said filtration slit [212] is reversed with respect to the direction of the flow in said operative position so that said filtration slit [212] is backwash； and characterized in that the apparatus additionally comprises f) a cofiltration element and in which in said operative position, said filtration slit [212] is aligned with said cofiltration element [240] to block the passage of particles from said source of fluid through said filtration slit [212] and in said purge position said filtration slit [212] is positioned to purify said cofiltration element [240] allowing particles of said fluid source to pass through said filtration slit [212] and exit out said purge outlet [209].Un aparato para filtrar un fluido para un emisor de riego que comprende: a) una salida de riego [226]； b) una salida de purgación [209]； c) un conducto de entrada [204] conectable con una fuente de fluido； d) una cavidad [216] que tiene al menos tres abert
