Rain Water Harvesting System has become one of the necessities in an apartment. This system helps people to face the acute water shortage in various places. The Cochin builders are installing this system in almost all their projects.

In huge apartments proper arrangements should be made to utilize the rain water. The filtering system in large rooftop areas should accommodate the excess flow of rain water. The system consists of three concentric circular chambers in which the outer chamber is filled with sand, the middle one with coarse aggregate and the inner most layer with pebbles. The area of filtration is greater for sand in comparison to coarse aggregate and pebbles. The water reaches the central core and is then collected in the sump after which it is treated with tablets of chlorine and is purified for consumption.

Varun is another kind of filter which is made from a 90 litre High Density Poly Ethylene (HDPE) drum. The lid is turned over and is punched with holes. This first sieve keeps out large leaves, twigs etc. The rain water coming out of this sieve is then passed through three layers of sponge and a 150mm thick layer of coarse sand. The cleaning process is made easier by the sponge. The sponge should be removed and cleaned occasionally.

Rain water harvester was launched by EA Water Pvt Ltd. It filters runoff water from roads containing oil and grease. The filter has a sand filter which filters silt from runoff harvested from roof, lawns and parking area.