Shortage of potable water supply in urban areas is one of the main problems which is being faced by all countries including developed countries of the world. Human beings can not survive without water even for a day. The underground water is depleting day by day everywhere, whereas population of urban areas is increasing at alarming rate, mainly, due to migration of population from rural areas to urban areas and hence increasing the demand of water. In urban areas, the charging of underground water in natural way like rural areas is not taking place due to large sprawl of urban settlements.

Moreover, due to non charging of rain water during rainy season, the urban areas are causing heavy floods. These floods destroy urban infrastructure and crops of suburban areas every year during rainy season. Hence, there is a necessity to propagate harvesting of rain water in urban areas.

Rain Water Harvesting Techniques:-
In Urban areas rain water harvesting can be divided into two categories as described below.

1.Rooftop Rainwater Harvesting:-
The rooftop rain water harvesting system requires four elements i.e. a catch-ment area, (ii) conduits, (iii) settlement tank and (iv) recharge or storage facility. For rain water harvesting system, a dried bore well, an underground tank or soak pit are required along with conduits or the pipes carrying rain water from the catchment or roof tops to harvesting/storage system.

•Roof Catchment:
The roof of the house is used as the catchment for collecting the rainwater. The style, construction and material of the roof effect its suitability as a catchment. Roofs made of corrugated iron sheet, asbestos sheet, tiles or concrete can be utilized as such for harvesting the rainwater. But thatched roofs are not suitable as it gives some colour to water and also the water carries pieces of roof material (such as palm leaves).

•Gutters:
Gutters are channels fixed to the edges of roof all around to collect and transport the rainwater from the roof to the storage tank. Gutters can be prepared in semi-circular and rectangular shapes. Locally, available material such as plain galvanized iron sheet can be easily folded to required shapes to prepare semi-circular and rectangular gutters. Semi-circular gutters of PVC material can be readily prepared by cutting the PVC pipes into two equal semi-circular channels. Bamboo poles can also be used for making gutters if they are locally available in sufficient quantity. Use of such locally available materials reduce the over all cost of the system.

2.Storm Water Recharging Through Open Drains
In urban areas natural way rain water harvesting occurs only in areas left out for open spaces and parks. In the new areas which are being developed by the Urban Development Authorities / Civic bodies, the storm water is disposed off through underground channels of sewer lines, thus leaving no scope for recharging of this rain water into the earth.

The Haryana Government has made a step forward in this direction by making necessary provisions in the Building Bye Laws enacted under the Punjab Scheduled Roads and Controlled Areas Restrictions of Unregulated Development Rules 1963. The said Rules are described as below.

•The system of collection, conveyance and dispersion of rain water for harvesting shall be made in such a manner that only clear water is able to enter. No contaminated / waste water from the building or surrounding areas should find its way into the system.

•The entry points of the rain water for harvesting shall be designed in such a manner that in normal days these remain covered. Arrangement of segregation of the rain water from the first shower (containing the wash
water) should also be provided.

•The arrangement for quick filtration of rain water shall also be made in the rain water harvesting well/tube-well, so that the rain water does not pollute or choke the strata.

•The complete system of rain water harvesting will be constructed within the area of the plot, defined in the zoning plan for the plot.

•The recharge well shall be located at a distance of not less than ten meters away from any structure handling sewage or industrial waste water (such as septic tank or effluent treatment plant). This minimum distance of ten meters will not be applicable to manholes or sewer lines although it will be ensured that they are leak proof.