WLFILMAT self-cleaning filters have been designed with innovative solution regarding the efficiency of the system for the selfcleaning of the cartridge, thanks to newly designed back-wash on counter-current which grants the highest particles removal from the cartridge. When the cartridge is to be cleaned, the cleaning operation with back-wash is simply operated by opening the discharge ball valve at the filter bottom. That operation causes a pressure-drop which pushes the cartridge downward the housing bottom and reverses the water flow from the outer to the inner side of the cartridge. It is that counter-current back flow which washes away to the discharge the impurities trapped onto the outer side of the cartridge. The filters perform 90 micron filter rate with stainless steel net cartridge or plastic net cartridge and 50 micron filter rate with pleated plastic net cartridge.