Friday 17 February 2012

It is important that the system is sized to meet the water demand throughout the dry season. In general, the size of the storage tank should be big enough to meet the daily water requirement throughout the dry season. In addition, the size of the catchment area or roof should be large enough to fill the tank.

Ancient period


Rainwater harvesting has been used since biblical times. It was done in ancient Palestine, Greece and Rome. Around 3rd Century BC., farming communities in Baluchistan and Kutch used it for irrigation.[5]In Ancient Tamil Nadu, India, Rainwater harvesting were done by Chola kings.[6]Rainwater from Brihadeeswarar Temple was collected in Sivaganga tank.[7]In the Indus Valley Civilization, Elephanta Caves and Kanheri Caves in Mumbai rainwater harvesting alone has been used to supply in their water requirements.

Now


  • Currently in China and Brazil, rooftop rainwater harvesting is being practiced for providing drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels. Gansu province in China and semi-arid north east Brazil have the largest rooftop rainwater harvesting projects ongoing.
  • In Bermuda, the law requires all new construction to include rainwater harvesting adequate for the residents.
  • The U.S. Virgin Islands have a similar law.
  • In Senegal and Guinea-Bissau, the houses of the Diola-people are frequently equipped with homebrew rainwater harvesters made from local, organic materials.
  • In the United Kingdom water butts are often found in domestic gardens to collect rainwater, which is then used to water the garden. However, the British government's Code For Sustainable Homes encourages fitting large underground tanks to new-build homes to collect rainwater for flushing toilets, washing clothes, watering the garden, and washing cars. This reduces by 50% the amount of mains water used by the home.
  • In the Irrawaddy Delta of Myanmar, the groundwater is saline and communities rely on mud-lined rainwater ponds to meet their drinking water needs throughout the dry season. Some of these ponds are centuries old and are treated with great reverence and respect.
  • Until 2009 in Colorado, water rights laws almost completely restricted rainwater harvesting; a property owner who captured rainwater was deemed to be stealing it from those who have rights to take water from the watershed. Now, residential well owners that meet certain criteria may obtain a permit to install a rooftop precipitation collection system (SB 09-080).[8] Up to 10 large scale pilot studies may also be permitted (HB 09-1129).[9] The main factor in persuading the Colorado Legislature to change the law was a 2007 study that found that in an average year, 97% of the precipitation that fell in Douglas County, in the southern suburbs of Denver, never reached a stream—it was used by plants or evaporated on the ground. In colorado you cannot even drill a water well unless you have at least 35 acres. In New Mexico, rainwater catchment is mandatory for new dwellings in Santa Fe.[10]
  • In Beijing, some housing societies are now adding rain water in their main water sources after proper treatment.

Professor Micheal McGinley established a project to design a rain water harvesting prototype in the Biosystems design Challenge Module in University College Dublin.

  • In Australia rainwater harvesting is typically used to supplement the reticulated mains supply. In south east Queensland, households that harvested rainwater doubled each year from 2005 to 2008, reaching 40% penetration at that time (White, 2009 (PhD)).

In India


  • In Tamil Nadu, India rainwater harvesting was made compulsory for every building to avoid ground water depletion. It proved excellent results within five years and every other state took it as role model. Since the implementation, Chennai saw 50 per cent rise in water level in five years and the water quality significantly improved.[11] [12]
  • In Rajasthan, India rainwater harvesting has traditionally been practiced by the people of the Thar Desert. There are many ancient water harvesting systems in Rajasthan, which have now been revived [13]
  • Kerala, India,

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