Rain Water Harvesting

What is roof water harvesting?

The principle of rain water harvesting from roof- top is to collect and stored whatever amount of rain water that could be stored and diverting the rest for recharging the ground water.

At The Art of Living Ashram campus more than 42 lacks liters of rain water is currently collected and diverted to a tank.

Importance :

By the year 2050, there will be a steep fall in the availability of potable water. It is imperative to augment our water resources.

Fresh water is a crucial for all living beings. It is also essential for any development in Agriculture or industry. With a rise of population in India, there was a deduction in availability of water by 25% in the last 20 years and the picture remains gloomy further.

Currently a city like Bangalore is utilizing an average of 135 liters of water per capita/day. It is as low as 20 to 30 liters in some parts. In rural and drought prone areas, it could be a struggle to fetch a pot or two of water from distance places. By the 2050 AD, there would be a further steep fall in the availability of potable water to an extent of 35 to 40%. World Wide Fund (WWF) indicates that glaciers are melting at an accelerated rate and that “up to a quarter of global mountain glacier mass could disappear by 2050”. With receding Himalayan glaciers 800 to 1000 million people and 37% of irrigated land would be affected.

Floods followed by reduced flow in rivers and finally drying of some of them have serious consequences. Exploitation of ground water resources without adequate recharge may be catastrophic. When bore wells are dug in the “Shear Zone” as in most dry areas, with massive rocks below 200ft from surface, fluoride problems occur as Kolar district and Arsenic problems intensify as in west Bengal. Thus ground water for irrigation or for drinking is dangerous affecting the food-chain with toxins. Therefore, recharging bore wells is possible for percolation methods through soak-pit of dimensions of 13’ X 10’ X 10 filled with stones, pebbles and nylon filter mesh. It is necessary to improve tanks as well as to recharge the ground water. De- silting, maintenance of structures and distribution of water should be managed by Water- Users themselves.

Roof-top rainwater harvesting is not new in Rajasthan and Gujarat people through ingenuity have managed to survive worst famine – situations with only 150 mm rainfall in some years! There is absolutely no way to augment our water resources other than effecting all round savings, capturing every drop of rain that falls on the soil and on our roof tops i.e. WATER HARVESTING in the fields and ROOF WATER HARVESTING from our residences and offices. In such buildings, the principle of rainwater harvesting from roof – top is to collect and store whatever amount of rain water that could be stored and diverting the rest for re-charging the ground water.

It is estimated that a 1000 sq. m. roof – area with about 890 mm annual receipt of rainfall in Bangalore, can yield over 8 lacks liters of water. Of this 2 to 3 lacks water can be harvested and stored in sumps (cement ring wells) prepared in the run ways of car parking spaces for use in 6 to 8 months of rain less periods. The rest could be diverted to recharge ground water at 8 to 10 meters depth through 3 to 4 PVC pipes around the building.

Prof. Dr. Shivashankar K.