Automatic backwash filter is composed of the drive mechanism, the control circuit (including the pressure switch), filter components, cleaning device, connecting flanges and other major component parts.It cleans sewage by the drive motor and the electric valve automatically, the operation mode is automatic operation (option:manual operation), with timing control or pressure difference control. Its automated part is controlled by reliable PLC programmable controller. Water enters into the filter, the mechanical impurities are intercepted.When the impurities accumulate for a period, reaches 0.05MPa, then the differential pressure switch will send signal, while the PLC command is issued, transmission motor starts, the drain valve opens, the impurities deposited on the filter is brushed away, and drain out. The whole process is without personnel, without downtime. Besides, the device also has the function of timing and manual cleaning to ensure that the outlet water is safe under any circumstances.