ECO / WATER SPECIAL... Harvest That Raindrop

 Harvest That Raindrop 

Saving that drop of rain will save us from water stress. Begin by incorporating rainwater harvesting systems at the time of designing homes or office. Such systems can cut down costs in the long run by reducing dependence on govt-provided water

    At a time the monsoons have been quite active in the country, rainwater harvesting may be far from everyone’s mind. Yet, there is no better time to think about this. If you look at our concrete urban spaces, most of this water literally goes down the drain. Many of our cities and states have rules enforcing rainwater harvesting, yet very few homes and commercial buildings have implemented it. Excuses range from the cost of construction to lack of knowledge. Yet individuals who have incorporated such systems say that integrating water harvesting actually reduces costs over the long run. “I have not used corporation water since 1994 in my home. We have used only harvested rain water and ground water that is recharged with rain water,” said A R Shivakumar, Senior Fellow at Karnataka State Council for Science and Technology (KSCST). His home, constructed in 1994 in Bangalore, was built with the objective of being as eco-friendly as possible. “With planning, rain water harvesting does not have to be expensive and space consuming,” said Shivakumar, who made a presentation on his home at an event on green homes organised by Bangalore-based site on sustainability, The Alternative. Here are some tips:
Tank it Up
Multiple rainwater tanks can be built depending on the flow of water. For instance, at Shivakumar’s home there is a 4500-litre rooftop tank. The excess water from this tank is allowed to run down rainwater pipes to a 25,000 litre sump built under the portico. If these two tanks fill up, then the extra water is allowed to seep into the ground. A different set of rainwater pipes from the terrace takes water to a 10,000-litre tank built under the car park. The two underground sumps are interconnected and built at different depths so that water can flow from one to the other. The second sump is also linked to a borewell, which is used when the water in the tank gets depleted.
Sieve and Filter
The first rainfall has a number of pollutants, so a first flush valve flushes out the dirt. Installing filtration systems before the water goes into the storage tanks is important. The traditional one is the sand bed filter, with various beds of sand, gravel and pebbles, which strain out impurities. There are other smaller filters that are more effective and save space as well. For large spaces and heavier loads of water, you will need to install bigger tanklike filters to clean out the contaminants.
Zero Wastage
Some of the water can be reused as well. For instance, water used in a washing machine can be collected in a separate tank and after filtering, used to flush the toilet. In cities with heavy rainfall, most rainwater harvesting sumps are not enough to hold all the water. You can ensure overflow outlets for all underground sumps. The outlets can be diverted into large plastic drums buried underground with their bottom cut off. Also by not paving or concreting open spaces any rainwater falling onto the garden can percolate into the ground. You can also leave out open pots that will act as birdbaths when they fill up with rain water.
Of the population in Brazil, Russia, India and China together are living under medium to severe water stress; this share will increase to 80% by 2030 unless new measures to better manage water resources are introduced, says an OECD Environmental Outlook report

Radhika P Nair ET130727