Rain is the most important source of all water on earth. Water cycle is unique. In an endless cycle, rain rejuvenates all fresh water resources. Rainwater recharges the surface sources and slowly seeps into the ground to reach and replenish the underground aquifers. The present water crisis is a result of our failure to appreciate this primary source of all water on earth. In the last few decades rapid urbanization has spread across the country.The population of urban dwellers has risen to manyfolds. It is expected by the year 2025 more than 50 % of the country population will live in towns and cities. Because of this population explosion, the demand for water has risen sharply. As summer approach the demand for water increases further, where the supply remains low. Today many cities in India are facing acute water shortage. Groundwater being accessible with easy to extract techniques and today is under great stress .Our Groundwater levels have declined sharply in most urban areas. In some aquifers, the fresh water is underlined by brackish water. As more and more ground water is pumped out, brackish water raises thereby contaminating the fresh water, making it unsuitable for drinking. In coastal areas, there is always a threat of seawater intrusion into freshwater reserves; as a result tubewells are downed to extract more ground water. Today, we face serious water crises, because while ground water continues to be pumped out in huge quantities, very little water is recharged into aquifers. With rapid urbanization, lakes, ponds and green areas that contribute to recharge have reduced drastically. Catchment areas have been paved and reclaimed for construction. As a result even when the rains come, no recharge can take place. Each year, Gujarat state receives quite substantial amount of rainfall. But in urban areas, this rainwater is unable to seep into the ground, because the land is ceiled for miles with concrete buildings and a network of roads. Instead, this precious rainwater rushes out through drains, nallas and flows out into rivers and to the sea.Billions of litres of fresh water are lost each season in this way. The runoff of urban areas is heavily polluted. Due to an inefficiency of the system and careless disposal of garbage all around, the waste water flowing around the steams seeps underground and pollutes the fresh water aquifers. In Low lying areas, the downpour leaves the city water logged. Roads get flooded as the natural drainage systems are blocked. The water slowly evaporates and no recharge can take place. In urban areas, the need for rainwater harvesting is critical. Water is already a scarce commodity and as its demand increases further, the situation is piled up uncontrolled. Rainwater harvesting is simply catching rain where it falls and using it to storage and recharging the aquifers. Everybody can harvest rain. All that is required is a catchment area. The surface that receives rainfall directly on the roof of the building or terrace or courtyard. It also needs pipe line and drains. Most houses already have done this. This carry the rainwater to the gutter. It is here that a small change can be made. This change consists of diverting rainwater either towards storage tank or to a recharge structure. Rainwater can be harvested through various structures. The construction of these is dependent on the existing geological conditions of the area. It is therefore important to understand which structure is suited for which situation. Hilly areas like Surat, Valsad and Dangs of south Gujarat receive high rainfall and have high surface runoff. They are not suitable for storing rainwater. Hydro geological conditions are not conducive for recharge. Water can be harvested by storing rainwater into tanks on the surface or underground. Desert areas receive low rainfall. The water table here is very deep. In such areas, it is beneficial to store water in suitable structure as practiced in the state of Rajasthan. Areas which have a very thick top impervious layer don’t allow rain water to percolate down. These places suffer from frequent water logging and are not suitable for recharge structures. Constructing Recharging wells would be very expensive. The best alternative is to go for storage. Areas with the top pervious layer are more suited with direct recharge structures like Recharge pits, trenches and abandoned wells and tube wells. To build these structures, it is essential that the water table is at least 8 m below ground level. Unsaturated zones above the water table provides space for storage of water and also allows natural filtration of water percolating down. Earlier dug wells and tube wells used to extract groundwater. Many of them have gone dry because of declining water levels. These abandoned structures can be utilized after proper cleaning. This can save constructional cost. In small houses, or campus, rainwater collected from the roof top terrace is diverted by down pipes to a filter mesh to a filtrating chamber of filtration tank. These tank filter silt and other impurities and also acts a storage tank for storing excess run off. From here this water is diverted to the recharge structure which may be a pit, trench or abandoned structures or a combination of these depending upon the requirement. Usually the front yard of the house slopes in to the road, water therefore flows out. The drain of the house can be designed in such a way that there is slight dip in the centre forming a trough. A trench can be made to adsorb the rainwater. In a locality level, water harvesting system like a in an apartment block rainwater runoff from an individual houses can be harvested in common areas. Colonies should collectively build rainwater harvesting structures, so that precious rainwater is not lost to drains in gutters but goes to replenish the aquifers. Millions of liters of rainwater can be harvested in this simple way During the monsoons, a lot of water accumulates in the low lying areas of garden, parks and ponds. And remains stagnant for long periods. This water can be harvested by making pits with or without a bore well in the low lying area The pit should be filled with filter media, such as boulders, gravel and coarse sand in graded form. The bore well should end in the permeable formation. With growing urbanization, paved areas such as roads and parking areas are increasing day by day. These provide lot of surface run off during the rainy season. Strom drains with recharge pits, trenches or shafts can be constructed to recharge. Recharge pit/soak pit It is constructed 1 – 2 m wide and 3 m thick. It is backfilled. This structure is suitable for small houses. The recharge trench or campus is across the slope of the ground constructed along the boundary of the house. The trenches are built ½ to 1 m wide and 2 – 20 m long depending on the requirement. It is backfilled with a filter media. In areas which have a thick top impervious layer, rainwater is not able to directly seep into the aquifer. Here a recharge structure needs to penetrate the thick impervious layer to reach the pervious layer. For recharging the deeper aquifers, shallow shaft with recharge well is constructed. The shaft is 2 – 5 m in wide and 2 – 4 m deep, it is backfilled with filter media. Inside the shaft a recharge well is constructed to recharge the stored water. A recharge well is like a normal tubewell. It penetrates the impervious layer and ends in the aquifer. An abandoned well or a tube well can be used to recharge the deeper aquifer after proper desilting. In some areas such as hilly regions like surat, valsad and dangs groundwater recharge is not feasible. Due to hydrogeological conditions over there. But these areas receive heavy rainfall. The runoff can be stored in tanks for domestic use. But this runoff is directed from the roof area, by a pipe towards the storage tank. A mesh filter at the mouth of the drain prevents leaves and debris from entering. Device from the down pipe ensures that the first runoff from the first shower is flushed out as it may carry pollutants from the air. The water can then be diverted to a charcoal of water filter for filtration of the first water. For drinking purposes this water should be properly used The settlement water from the storage tank is constructed near the well for desilting of the runoff and storing the excess water. Clean water from the settlement tank is then diverted to the recharge well for recharge. There are some important things to keep in mind Use abandoned structures eg. Tubewells , dugwells etc In the absence of abandoned structures, make recharge pit/trench Make a borehole in recharge pit/trench/if the formation is impervious Make a shaft if the top layer is impervious and area is large. Make shaft with recharge well if area is large and aquifer is deep Use a existing tubewell for roof top rainwater harvesting and use online filter When recharge structure is not possible, store rainwater in tanks. There are also some precautions to be taken Don’t divert or inject industrial sewerage water into the recharge structures Don’t inject highly turbid water into the recharge structures Periodically clean the filter media Maintain the recharge structures properly Don’t recharge the shallow water table area, unless it is 8 m below the ground level A collective and a united effort are required to make rainwater harvesting a successful effort. If each every houses and locality can practice rainwater harvesting, water will never again be a short supply.