Main Category :Sanitation Sub Category :Sanitation Leelananda Jayasuriya Basically Inverted flow filter is a slow sand filter. The structure is an open type water tight rectangular tank divided in to two compartments connected by a passage from bottom. When raw water is fed to the inlet tank water percolate through the filter media that comprises of fine sand and passes along the passage provided at the underside to the sand bed of other compartment. This structure behaves similar to "U" tube, filled water in it. Due to force trying to equalize the levels on both compartments this water passes over to the surface of the filter bed of the left side compartment as shown. In nature we find pure water in springs and in deep wells while polluted water resorces are found in nearby locality. Water filter from other resorces and avilable as consumable water in nature due to the similar phenomina occured under ground in this manner. In the above figure you can see the recepter compartment consist of flow diversifying structure to spread the flow on a wider area. If this type of structure is not constructed the upword flow will take part at the closest position to right hand side compartment. To perform this action only a little pressure head is required. It does not require the expensive construction of a suspended sand bed. This is better in performance