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Saving of Rain Water

“Conscious collection and storage of rainwater to cater to demands of water, forv drinking, domestic purpose and irrigation is termed as Rainwater Harvesting.”
The term rainwater harvesting is being frequently used these days, however, the concept of water harvesting is not new for India. Water harvesting techniques had been evolved and developed centuries ago.
An old technology is gaining popularity in a new way. Rain water harvesting is enjoying a renaissance of sorts in the world, but it traces its history to biblical times. Extensive rain water harvesting apparatus existed 4000 years ago in the Palestine and Greece. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water to augment water from city’s aqueducts. As early as the third millennium BC, farming communities in Baluchistan and Kutch impounded rain water and used it for irrigation dams.
Ground water resource gets naturally recharged through percolation. But due to indiscriminate development and rapid urbanization, exposed surface for soil has been reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource. Rainwater harvesting is the process of augmenting the natural filtration of rainwater in to the underground formation by some artificial methods.

Why rain water harvesting?

Rain water harvesting is essential because surface water is inadequate to meet our demand and we have to depend on ground water. Due to rapid urbanization, infiltration of rain water into the sub-soil has decreased drastically and recharging of ground water has diminished.As you read this guide, seriously consider conserving water by harvesting and managing this natural resource by artificially recharging the system.
The examples covering several dozen installations successfully operating in India constructed and maintained by CGWB, provide an excellent snapshot of current systems.

How to harvest rainwater?

Broadly there are two ways of harvesting rainwater:
(i) Surface runoff harvesting
(ii) Roof top rainwater harvesting

Surface runoff harvesting

In urban area rainwater flows away as surface runoff. This runoff could be caught and used for recharging aquifers by adopting appropriate methods.

Roof top rainwater harvesting(RTRWH)
It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes the catchments, and the rainwater is collected from the roof of the house/building. It can either be stored in a tank or diverted to artificial recharge system. This method is less expensive and very effective and if implemented properly helps in augmenting the ground water level of the area.

Advantages of rainwater harvesting
  • Makes use of a natural resource and reduces flooding, storm water runoff, erosion, and contamination of surface water with pesticides, sediment, metals, and fertilizers.
  • Reduces the need for imported water (the San Diego region imports between 80%-90% of its water from Northern California and Colorado River).
  • Excellent source of water for landscape irrigation, with no chemicals such as fluoride and chlorine, and no dissolved salts and minerals from the soil.
  • Home systems can be relatively simple to install and operate May reduce your water bill.
  • Promotes both water and energy conservation.
  • No filtration system required for landscape irrigation.

Disadvantages of rainwater harvesting
  • Limited and uncertain local rainfall.
  • Can be costly to install – rainwater storage and delivery systems can cost between $200 to $2,000+ depending on the size and sophistication of the system.
  • The payback period varies depending on the size of storage and complexity of the system.
  • Can take considerable amount of time to “pay for itself”.
  • Requires some technical skills to install and provide regular maintenance.
  • If not installed correctly, may attract mosquitoes (i.e.; West Nile Disease and other waterborne illnesses).
  • Certain roof types may seep chemicals, pesticides, and other pollutants into the water that can harm the plants.
  • Rainwater collected during the first rain season is generally not needed by plants until the dry season Once catchment is full, cannot take advantage of future rains.

Latest News

  • TN's success story: Rain water harvesting

  • Rain water harvesting is considered the answer to India’s water woes. The practice has been patchy in many parts of the country, but Tamil Nadu’s experiment with the alternative water conservation technique is a rare success story.

    The Rain Water Harvesting (RWH) scheme, a brainchild of Tamil Nadu chief minister J Jayalalithaa, was launched in 2001 in a bid to rejuvenate water sources and improve ground water levels in the parched southern state.

    The programme got off to a rocky start because of fierce resistance from residents after the government made it mandatory for all government and residential buildings. But nearly 15 years down the road, the tables have turned, so to speak.

    The scheme has helped people in water-starved regions such as Chennai by raising water tables in most neighbourhoods, winning support from activists and local residents long dependent on groundwater for their daily needs.

    The scheme has been implemented in rural pockets too, with a great degree of success. “We used to spend sleepless nights, thinking about sourcing water for daily needs. All that changed after the government came up with the RWH method. The water table has risen and we no longer face such an ordeal,” said Vanitha, a Chennai resident.

    Chennai owes its success to a change in rules to ensure that new buildings didn't get the nod from authorities without rainwater harvesting structures. With more and more residents migrating to the suburbs from the city to overcome the water-related issues, the scheme has come in handy to make sure that there is no shortage.

    Shekhar Raghavan, director of the Rain Centre, said Chennai has a head start because it has completed 70% of the work while other cities are getting started on the scheme. “Chennai has done a good job on the RWH front when compared to other cities/districts. In Tamil Nadu, urban harvesting is better when compared to the rural ones,” he said.

  • Rainwater harvesting policy before monsoon

  • NEW DELHI: The Delhi Jal Board ( DJB ) has finalised its rainwater harvesting policy and plans to roll it out before the onset of the monsoon.

    Having issued new, simplified designs for RWH structures, the water utility has given residents time till June 30 2016 to install the same, failing which a penalty equivalent to 50% of the monthly water bill will be levied on defaulters. While RWH has been mandatory in the city for several years, implementation has been extremely lax, followed by poor maintenance of existing structures.

    DJB officials said that once the policy was implemented, a physical verification of structures would be carried out before the onset of monsoon each year. Action will be initiated if they are not properly maintained.

    All PWD buildings will be made RWH compliant by April 2017. The urban development department will prepare a list of all government buildings, which do not have rainwater harvesting facilities. Such buildings will be served notices and they will be told to implement the new structural designs at the earliest. A meeting will be held with the Delhi Metro separately to work out details of RWH at its stations and platforms.

    The latest policy was framed by the Delhi Dialogue Commission and DJB. Sources said DJB officials had spent considerable time in Chennai, which has successfully implemented rainwater harvesting. Water expert from Chennai Sekar Raghvan helped DJB frame the policy and recommended structural designs.

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