L-type water filters are fully automated with a PLC system for automatic operation, self-cleaning filter, no water to wash the anti-based high-tech automatic water treatment equipment. The device is a multi-cartridge filter, reverse single-washing structures, it has a large area of filter, equipment small and compact, high-efficiency filter, backwashing strength, less water consumption, etc., and the filtration and discharge sewage operate at the same time. Does not affect or interrupt the normal use of the system.