RAIN WATER STORAGE TAKES CENTRE STAGE

RAINWATER, the ultimate solution to the drinking water crisis for ages, has been the nation’s primary source of water. In the arid and dry areas of India, ingenious rainwater storage tanks have served the purpose of catering to our needs.

Rainwater harvesting, the buzz word in today’s ecological context, comprises of water storage and water recharging. Though water recharging has been the prime focus till now, rain water storage is being realised as an equally important process that lends efficiency to the entire exercise, says S B Dangayach – Managing Director, Sintex Industries Ltd.“The cost of purifying around 150 litres of water per head per day far exceeds the cost of rain water storage for the WHO specified requirement of 5 litres for drinking and cooking, which exerts enormous pressure on energy resources,” he adds.

Properly stored rain water can yield us a huge reserve of pristine water fit for human consumption. A typical rain water storage system consists of purification and a storage component, in which water collected from roof tops and catchments areas is filtered and stored in proper sanitized tanks. Dangayach says rain water storage can be promoted by sensitising masses to its benefits, installing the system in maximum places, implementing the ‘Rajiv Gandhi National Drinking Water Mission’, changing the bye-laws to make rain water storage compulsory in select areas, and to allow packaging and selling of rain water for consumption.

“By focussing on rainwater collection and storage, we can make drinking water easily available in many parts of the country. Sintex has over the years pioneered and developed the rainwater storage systems in India, and offers a holistic system for rain water storage,” concludes Dangayach.

Rainwater harvesting basics

Rainwater harvesting means collection of rainwater that falls on the roof of a house, apartment complex, commercial building, a factory or any other area.

This can be channelised through a drainpipe, allowing the collected water to flow into a well or a storage tank with a filtration set-up. In case it goes to a well, this will result in increasing the water table.

In places close to the sea, this prevents seawater from seeping into the underground water table. Even if one does not have storage set-up, merely allowing collected rainwater to percolate underground raises the groundwater table.

For residential complexes with water supply issues, the stored water can be used for immediate consumption also.

Components of Rainwater Harvesting System

The first component is the catchment area (terrace, courtyard or lawn), where one can collect rainwater. Alternately, a temporary set-up during the monsoon, like a tarpaulin cover or a sloping shed can also be a catchment area. The quantity of rain water that can be generated by these is determined by the run-off factor (water flow).

Ideally, a location with some green cover makes a better catchment area. Tiled surfaces should be porous, to allow percolation in courtyards or compounds.

Next are the conduits: the pipes that carry the rainwater from the catchment area to the harvesting or storage system.

The third component is the settling tanks, which clean the rainwater of impurities and also act like a buffer to store water. These are basically storage containers where insoluble impurities are allowed to settle down to the bottom of the tanks, or where water is purified/ filtered and then, moved to the recharge or storage facility. Underground tanks made of bricks or RCC, or old water tanks that are not being used can be used as settling tanks. The bottom and sides of this container should have loose rubble and bricks to encourage percolation. The bottom of the tank must be filled with sand, gravel or metal to filter impurities.

Finally, there are recharge or storage facilities: a structure of shallow depth, like a trench, although it can also be deep, like a bore or open well, which is connected to the housing complex’s water supply tank. A recharge pit can be constructed near a well in the compound, the well acts as a storage facility.

Keeping rainwater fresh

Collected rainwater can be kept fresh by taking the following precautions:
Rainwater of the first week should be run off, to avoid collecting dust.
The storage tank should be properly sealed
make sure sunlight does not enter the tank
Chlorine or lime can also be used to keep the water tank clean

Source : Times of India