Bangalore is a city located on an altitude of over 900 m above sea level. It has no perennial river flowing into it. The city receives water mainly from the Cauvery, providing for more than 70 per cent of the city’s requirement. It also receives water from Hesaraghatta and Thippagondanahalli reservoirs.

There is a huge energy cost involved in the supply of water. The Bangalore Water Supply and Sewerage Board (BWSSB) has to pay nearly 60 per cent of its revenue to Bescom since the energy cost of pumping is huge. The demand for water is growing in direct proportion to the City’s growth. All this means that it is imperative to protect and sustain its water sources and rainwater harvesting is one of the ways of doing it. Thankfully, major initiatives have been taken in the corporate sector.

One of the many measures taken up by Bharat Electronics Limited (BEL) to save water, reduce water consumption and recharge ground water table is the Rain Water Harvesting project initiated in 2000. The project stores rain water during monsoons for later use, thereby reducing the water consumed from other sources. Known to be the first of its kind to be constructed by any public sector industry in India, the capacity of the rain water harvesting reservoir near the north gate of the factory is 170 million litres, completed at a cost of Rs 57 lakh.

This project not only significantly augments the water supply needs of the factory but also benefits the surrounding area and society. People living in the surrounding areas have reported recharge of borewells.

The Tata Energy Research Institute (TERI) was approached to make a feasibility study on the project. Their report revealed that rain water harvesting system could be established successfully at the proposed site. The preliminary study also brought out that the project could harvest rainwater to the extent of 234 million litres per year, which is equivalent to 650 kl per day.

A detailed study identified the area near the north gate of the factory for receiving and storing rainwater from the colony area. An earthen pond was proposed to store 135 million litres of water. The study, based on 100 years’ rainfall pattern and 28 years of average rainfall disclosed that there was a possibility to harvest about 500 ml of water annually, assuming an average rainfall of 476 mm. The design, proposed by TERI, was accepted and the work that commenced around November 2001 was completed by February 2002. The earthen pond was constructed in the north east corner of the estate. The embankment with an enclosed area of 37, 229 sqm (10 acres) was constructed in a record time of 120 days. The storage capacity of the pond is 170 million litres and it has started functioning.

The required infrastructure has been created to utilise the water for horticultural purposes and as the quality of water is expected to improve over a period of time, this water will eventually be used for other applications including industrial process. The silver lining is that the low hardness of rainwater is preferred for certain industrial processes.

A similar initiative has been undertaken by Wonderla amusement park, which is perhaps the only such initiative taken by an amusement park in the country. Wonderla has adopted rainwater harvesting and water management techniques. The amusement park is 28 km from the City on Mysore Road, located in an area of 87 acres in Jadenahalli in Bidadi Hobli of Ramanagaram district. As the entire park is on a slopy terrain, it facilitates rainwater harvesting in a greater measure.

“We use reverse osmosis in the treatment of water, the same process used in the bottling of mineral water,” says Arun K Chittilappilly, Executive Director.

Reverse osmosis, also known as ultra-filtration by the industry, represents state-of-the-art in water treatment technology. Reverse osmosis (RO) was developed in the late 1950's under US Government funding, as a method of desalinating sea water. Today, RO has been regarded as the most convenient and thorough method of filtering water. It is used by most water bottling plants and by many industries that require ultra-refined water in manufacturing. Now this advanced technology is available to homes and offices for drinking water filtration
Says Karuppiah Kathiresan, senior engineer - mechanical, “Although the total area of the amusement park is 87 acres, the catchment area for rainwater harvesting is 20 acres. Storm water drains have been created and the water flows into an artificial lake (tank) created for the purpose at the steep end of the amusement park.

The lake has a capacity of 1.6 crore litre. During 2007, as much as 5 crore litres of water was harvested from January to December. Just two or three heavy rains are enough for the lake to fill up. Therefore, it has been decided to create another lake of a similar capacity. The water collected through rainwater harvesting is used in washing, gardening and amusement pools. The water collected undergoes pre-treatment process and is then treated using the RO process.

Water is also harvested from rooftops of the various buildings and structures - about 10 to 12 buildings. The water is tapped from a total roof area of 2 lakh sq ft and is conveyed through closed pipes to a tank with 5 lakh litre capacity. The water is treated by RO process and used for drinking. A 15-minute rainfall is enough to fill the 5 litre tank.