Jun 20, 2007

RWH (Rain water harvesting)

Harvest the water for a better tomorrow


In today’s world where rich man on one side of the globe has made a easy way of throwing away waste by diluting and mixing it with water and it being wasted for mere washing and cleaning purposes and with no proper drainage system being maintained. One the other side a poor man is striving hard to get a bucket of water for drinking. With bore wells being dug hundreds of feet; water is surely going to become scarce soon. Fortunately water is available now but very soon if proper measures are not taken the ground water is soon going to be vanished. In this situation I would like to highlight few basics on rainwater harvesting. I have collected information from various websites, Please follow the links if you are interested about a individual topic. There are also few videos which u might find interesting as well at the end.


Rain water harvesting is conserving water right where it falls. Rain water harvesting can benefit in following ways.
1) It improves ground water quality & quantity both. There is no other technique available for the same.
2) It prevents saline water intrusion in ground water from sea in coastal area.
3) It increases ground water table & hence decreases pumping costs.
4) Water logging in low lying area can be reduced upto certain extent. Hence, rain water harvesting, water recycling & water treatment are cheapest & easiest technique to overcome water problems.


In ancient days itself, people, especially Indians, know the methods of conservation of rainwater. There are evidences that, even during Harappan period, there was very good system of water management as could be seen in the latest excavation at Dholavira in Kachch. During independence period, the people use to manage water resources considering it as part of the nature which is essential for their survival. This could be seen from the rain water harvesting structures in the low rainfall areas of Rajasthan, harvesting springs in hilly areas and mountainous region and percolation ponds and tanks in southern India.


In South India, the ancient people stored rainwater in public placed separately one for drinking purposes and another for bathing and other domestic purposes. They also formed percolation tanks or ponds, for the purpose of recharging irrigation or domestic wells. They periodically clean the water ways so as to get clean water throughout the year. These are instances in the history that people constructed crude rubble bunds across river courses either for diversion of water or for augmenting the ground water. The various methods of rainwater harvesting are classified below under two category, Traditional and Modern methods.


Traditional Methods

Traditional rainwater harvesting, which is still prevalent in rural areas, was done in surface storage bodies like lakes, ponds, irrigation tanks, temple tanks etc. In urban areas, due to shrinking of open spaces, rainwater will have to necessarily be harvested as ground water, Hence harvesting in such places will depend very much on the nature of the soil viz., clayey, sandy etc. The below listed are the various kinds of traditional rainwater harvesting methods. Click for more detailed info

Kunds of Thar Desert

Kul Irrigation Method

Bamboo Method

Temple Tanks of India


Modern Methods

The Modern methos of rainwater harvesting are categorised under two, they are Artifical Recharging and Rain Water Harvesting. The former is classified into Absorption Pit Method, Absorption Well Method, Well cum Bore Method and Recharge trench cum injection well. The later is categorised into Individual Houses and Grouped Houses which are further classified into Percolation Pit Method, Bore Well with Settlement Tank, Open Well Method with filter bed Sump and Percolation Pit with Bore Method.


Artificial Recharging

Absorption Pit Method

Absorption Well Method

Well cum Bore Method

Recharge trench cum injection well


Rain Water Harvesting in Individual Houses

Percolation Pit Method

Bore Well with Settlement Tank

Open Well Method with filter bed Sump

Percolation Pit with Bore Method


Rain Water Harvesting in Grouped Houses


RWH in Grouped Houses(Flat)


Rural RWH Methods

Rain water harvesting for Rural Areas





A model


For complete information on every detail please check http://www.aboutrainwaterharvesting.com/rwh_methods.htm

Rainwater is particularly useful to supply the large volume of water needed for flushing toilets. Each person on average uses almost 45 litres a day for this purpose. In an average household, this contaminates nearly 66,000 litres of drinking water a year. This is the main use of water in a household, closely followed by bathing and washing which uses 37 litres per person per day.

Rainwater is ideal for use in washing machines; on average people use 20 litres a day for washing clothes. The advantage is that the soft rainwater allows the use of natural soaps and biological washing powders, which are much more gentle on clothes than standard detergents. Not only this, there is less chance of skin irritation caused by detergents, and there is no environmental damage when discharged into the waste water system.

Gardeners through the centuries have recognized the importance of a plentiful supply of water, and that plants prefer natural rainwater instead of heavily treated mains water. A hosepipe uses a minimum of 500 litres an hour - almost as much as an average household uses in a day.

Rainwater can also be used for car washing and other general cleaning tasks around the home.


In commerce and industry

The use of rainwater can really come into its own in business and industry. Not only is water extensively used in a wide range of tasks, but there are often large roof and hard standing areas to catch rainwater. This provides an incentive to invest in rainwater harvesting equipment as business use can offer a relatively short pay-back period.

Rainwater can be used cost-effectively for water-intensive tasks such as dust control, cleaning processes during manufacture, washing vehicles and other specialised cleaning processes such as printed circuit board manufacture, and in agriculture and animal husbandry where farmyards and animal stalls must be regularly hosed down.

In large offices and public buildings, rainwater can be used for flushing toilets and urinals and for cleaning. Facilities managers are increasingly not only insisting these systems are installed on new buildings but looking to retro-fitting the equipment to existing buildings.


http://www.constructionresources.com/products/services/rainwater_overview.asp

Rainwater harvesting is the collection and storage of rain from roofs or from a surface catchment for future use. The water is generally stored in rainwater tanks or directed into mechanisms which recharge groundwater. This is appropriate in many parts of the world, such as western Britain, China, Brazil, Thailand, Sri Lanka, Germany, Australia and India, where there is enough rain for collection and conventional water resources either do not exist or are at risk of being over-used to supply a large population. Rainwater harvesting can provide lifeline water for human consumption, reduce water bills and the need to build reservoirs which may require the use of valuable land.

Traditionally, rainwater harvesting has been practised in arid and semi-arid areas, and has provided drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels. This method may have been used extensively by the Indus Valley Civilization.

Currently in China and Brazil, rooftop rainwater harvesting is being practised for use for all the above purposes. Gansu province in China and semi-arid north east Brazil have the largest rooftop rainwater harvesting projects ongoing.

Rainwater harvesting in urban areas can have manifold reasons. To provide supplemental water for the city's requirement, to increase soil moisture levels for urban greenery, to increase the ground water table through artificial recharge, to mitigate urban flooding and to improve the quality of groundwater are some of the reasons why rainwater harvesting can be adopted in cities. In urban areas of the developed world, at a household level, harvested rainwater can be used for flushing toilets and washing laundry. Indeed in hard water areas it is superior to mains water for this. It can also be used for showering or bathing. It may require treatment prior to use for drinking.

http://images.google.co.in/images?q=rain%20water%20harvesting&ie=UTF-8&oe=UTF-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&um=1&sa=N&tab=wi

http://en.wikipedia.org/wiki/Rainwater_harvesting

http://akash-ganga-rwh.com/RWH/WaterHarvesting.html

http://www.youtube.com/watch?v=FBUPL7E4G-0

http://www.youtube.com/watch?v=k_XXak6IQTA

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