Rainwater Harvesting
Technical methods to conserve water
Rainwater Harvesting :
Rainwater harvesting is a simple, economical and eco-friendly technique of preserving every drop of water by guiding the rainwater that falls to borewells, pits and wells through small diameter pipes.The traditional method of rain water harvesting is the most effective and simple way to conserve the water. It means utilization of rain water for the domestic as well as agricultural purposes.
Rainwater Harvesting in urban areas is the process of collecting, filtering and using of rainwater, which falls on the rooftop (terrace or tile roof) and in the portico of the house. Rainwater harvesting can be adopted in three methods. These are:
Borewell recharging By following the above method, we can recharge our borewells and keep them alive always. Those having open wells too can adopt this system. By directing the filtered rainwater to the open wells, their water tables could be improved. |
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| Ground water recharging | |
| Ground water recharging in urban areas is done by collecting the rainwater from the rooftops and the portico of the house and by making it easily absorbed within the veranda spaceThe method: An absorption pit should be constructed in the sloped area of the house veranda. The size of the absorption pit should be a minimum of 5 feet in width and a maximum of 10 feet in depth. Matching cement rings should be installed till the base of the pit. The pit should be filled with boulders (or big jelly stones) and a nylon curtain should be laid at the top. The remaining part of the pit should be filled with sand till one foot of the ground level. The pipe, which is installed for collecting the rainwater from the rooftop and the veranda of the house, should be linked to this absorption pit. Another pipe should be deployed for allowing the excess water to run off into the storm water drainage. Thus, by effectively preventing the rainwater from running off into the drainage and by making it absorbed into the ground, ground water sources can be recharged. All Bangaloreans, by adopting the ground water recharging system, can save the future generations the problem of water shortages. | |
| Reuse of rainwater | |
| Bangalore has an annual average rainfall of about 1,000 mm. It has been estimated that 2,23,000 litres of water can be collected annually from the rooftop of a 40’x60’ house with 1,000 mm rainfall. Assuming that, on an average, a Bangalorean spends 135 litres of water, a family of four would need about 2 lakh litres of water annually. So, water needed by an average family living in a 40’x60’ house could be collected from the rainwater falling on the rooftop. | |
| Rainwater Harvesting Method | |
| Water falling on a flat rooftop should be made to run through a pipe connected to the roof and prevented from running off to the drainage on the roadside. This water should be filtered and stored in tanks constructed for the purpose of storing rainwater. In case of houses with sloped rooftops (R.C.C., Tiles and Asbestos), a gutter should be attached to the roof and the water collected in it should be made to go through a pipe attached to the end of the gutter. The water, which runs down from the pipe, should be filtered and stored in the rainwater harvest tanks. A good quality filter is needed for purifying the water. This is because, although the rainwater is basically pure, the water flowing from the rooftop usually will contain waste material in it. | |
| Sand Filter | |
| There are two types of filters and sand filter is one of them. This filter can be built in the house itself. Before storing the later in a water tank, sump or drum, the water should be purified by making it flow through several layers of filtering. -One layer of boulders -Over that, one layer of big jelly stones -Over that, one layer of small jelly stones -Over that, one layer of charcoal -Over that, one layer of big jelly stones -Over that, one layer of small jelly stones -Over that, a layer of nylon curtain -Over that, a layer of sandLike this, a filter will have 8 layers. The rainwater will get purified when it flows through a filter prepared in this order. The purified water should be stored in a sump, tank or drum. The contents of the various layers of the filter should be changed once every five years. The water is filtered through the charcoal layer since the rainwater may sometimes contain poisons waste materials like bird excreta etc.No water connection if there is no rainwater harvesting system Keeping in mind the interest of the future generation, BWSSB has made a rule, which makes it mandatory for every house or building constructed in future to have a rainwater harvesting system in order to get drinking water connection.. There should be no connection between underwater drainage and rooftop waterIf the rainwater that falls on the rooftop is linked to the underwater drainage, there will be disorder in the underwater drainage system. If possible, the rooftop rainwater should be stored through the rainwater system. Otherwise, the rooftop rainwater should be linked to the storm water drainage system and should never be linked to the underground drainage system. First, a three feet slab should be taken out from the storm water drainage in front of the house. Thereafter, a trench of 3 to 5 feet should be dug and boulders should be spread on it and the boulders should be covered with a layer of sand. Through this system, water flowing though the storm water drain is absorbed into the ground and the ground water will be recharged. |
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| Always use MDPE Pipe | |
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