With the growing population there is a great demand for water. It is becoming very important to conserve water. Hence Kerala builders are emphasizing on the importance of rain water harvesting. Almost all the apartments are now being installed with the rain water harvesting systems. Due to the growing demand a variety of rain water harvesting systems have come up and one can choose from them depending on his needs.
In the coastal areas Horizontal roughing filter and slow sand filter are widely used. This filter is basically used to treat surface water and has increased the availability of safe drinking water. The major components of this filter are filter channel and a sump.
The filter channel is one square meter in cross-section and 8 mm in length, laid across the tank embankment. It consists of three uniform compartments in which the first is packed with broken bricks. The second one is made of coarse sand followed by a third compartment of fine sand. The filter material in the Horizontal roughing filter consists of gravel or coarse sand that successively decreases in size from 25 mm to 4 mm. The coarse filter media or the Horizontal roughing filter separates the bulk of solids in the incoming water. Fine graded mesh is implanted at every outlet and inlet point of the channel to prevent the entry of finer materials into the sump. The length of a channel depends on the nature of site selected for the sump.
Sump is the storage provision to collect filtered water from the tank through the filter channel.
Slow sand filter is a biological filter which is used to kill microbes in water. Both the filters are stable and do not make use of any chemicals. They make full use of the natural purification process of harvested surface water.