The polluted water entering from the inlet on the upper side of the filter slowly progresses downwards through the basalt sand. The particles in the water, whose specific gravity is generally lighter than the mass of the water, are held by basalt sand. The water that goes down by filtering passes through the mushroom nozzles in the inner chamber of the filter and proceeds to the lower chamber and then to the outlet of the filter. The increase of particles in the filter causes pressure loss in the filter. When the pressure loss reaches the specified level (0.5 bar and above), the filter must be subjected to a backwashing process. Backwashing can be done manually or automatically. In manual backwashing, the valve placed at the inlet is closed and the drainage path is opened manually. The water in the outlet is provided from the bottom up and the mushroom nozzles upwards, and the particles are discharged from the upper inlet section of the filter. In automatic backwash, 3-way valves connected to the upper entrance of the filter, solenoid control valves connected to them, electronic control unit and connections are used. If the differential pressure set in the control unit occurs or the specified time interval is completed, the upper inlet is closed by sending a command to the 3-way valves with the solenoid control valves, the drainage path is opened and the discharge from the bottom up takes place.