Ballis D. & Sons G.P. constructs filtering systems for various applications (Industrial and potable uses). The construction materials are always stainless steel and high pressure polymers in order to provide long lasting operation. The water flows through the filter from top to bottom driven by a pump. The filling material consists of multiple layers of quartz sand of different granule size and, in some cases, activated carbon and/or anthracite. All the suspended solids which are larger than the granule size of the filling material, are separated from the filtered water. When the pressure drops, the backwash mode is activated, and the back wash of the filter takes place in order to clean the filling material.

After the backwash, the filter is ready to operate as usual. The operation of the filter is managed by a PLC unit and the pneumatic valves are driven by an air compressor.