Conservation of water has become an important component for a greener tomorrow. The world requires a low cost clean supply of water for years to come. The rainwater harvesting techniques have been in existence since decades now. The rainwater is collected from the surfaces it falls on and stored in rainwater harvesting tanks. This water is either directly used, or purified to use it for drinking.
The nature has a ‘Water-Cycle’ to replenish the planet with water. Water from the oceans, seas, rivers and lakes is evaporated and when the clouds become heavy, they pour down as rain. Harvesting this rainwater is done by storing the rainwater collected from the rooftops. At some places, the rainwater is stored first and the excess water is used to recharge the ground water.
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The Structural Engineering Research Centre or SERC in India does research on building low-cost structures for storing rainwater, irrigation and sanitation. The institute teaches people in rural India to build ferrocement tanks to harvest rainwater and store grains. A ferrocement tank is created using cement and a structure made of steel bars and iron mesh wires. The rainwater is collected through pipes coming from the rooftops, and stored in these tanks. This method of rainwater harvesting is also prevalent in countries like Thailand, Malaysia and some countries of the African continent.
Rainwater harvesting for individual houses
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The rainwater falling on the rooftops is channelized through pipes into a water tank. There is a need to ensure that the rainwater is not wasted by travelling to the drains. If there is a well in the vicinity, the rainwater from the rooftops can be diverted to the well. Any excess rainwater may be used to recharge the underground water.
Rainwater harvesting for group houses
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A huge well can be constructed in-group housing complexes and rainwater from the rooftops of all the houses can be collected in the well/tank. A water purification filter can be installed in the complex to clean the rainwater. All the residents of the complex can utilize the rainwater collected and purified for drinking as well as other purposes.
Ground water dams
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This method of rainwater harvesting is used majorly in places where the underground water level varies. A dam is constructed underground to obstruct the flow of underground water and create a reservoir to store water. During the rains, the water percolates from the surface and reaches these underground reservoirs, increasing the water level by a considerable amount. The main advantage of these underground reservoirs is that the water is not polluted by the contaminants in the air. Also the water stored underground does not reduce by way of evaporation.
Ground water recharging
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The groundwater level is also increased by artificially recharging methods. An artificial pit is created in the ground, filled with sand and pebbles. On top of the pit is a chamber made for collection of water, reaching it through pipes form rooftops. In another method a well is built in the ground and is covered with concrete covers of appropriate thickness so that people and vehicles could move without restriction on top. Rainwater is channelized through pipes into the well.
Water is essential for living, humans, animals and plants all need water for survival. Unfortunately, it is the humans, who waste and pollute water, and we are responsible for the increasing scarcity of clean water. It becomes the duty of the humans to come up with ways to reduce water pollution and wastage so that the entire ecology does not suffer. According to Dr Prem Jagyasi, all should practice Rainwater harvesting techniques and everyone should understand the necessity of water conservation for a greener future.