At GT, we are obsessed. There are somethings we tell you again. And again! So what are we talking about today? Rain Water Harvesting (RWH), a green habit we all should include in our lives, homes and cities. Why? Because water is getting scarcer by the day. And there is never a better time to make a start.
Earth is a wet, wet planet. There is something like 1.5 billion cubic kilometres (15,00,000 billion litres) of water on Earth. But most of this water is salty. Subtract that and even then you have something between 12,500 and 14,000 billion litres of water available for human use annually.
Also consider this: Some parts of the world have more than they need, while others do not have any and get very little. Rivers have their own paths, and ground water reserves are not distributed diplomatically. In India for instance, Rajasthan with 8 percent of the country’s population has only 1 percent of the water, and Bihar with 10 percent of the population has 5 percent of it.
Traditionally, people across India built rainwater harvesting structures to get precious freshwater. Zings, kuls, kunds, bamboo pipelines, anicuts, johads, baolis—you are bound to have heard these names. The Britishers brought along the concept of centralised pipelines. Yes, we did get a unified water supply system but are we getting the water?
What is Rain Water Harvesting (RWH)?
Rain Water Harvesting is collection and storage of rain water that runs off from roof tops, parks, roads, open grounds, etc. This water run off can be either stored or recharged into the ground water. A rainwater harvesting system consists of the following components:
By 2025, more than 2.8 billion people living in 48 countries will face water stress or water scarcity, based on the recently revised United Nations population projections. By 2050 the number of countries which will face water stress or scarcity will rise to 54, and their combined population to 4 billion people – 40 percent of the projected global population of 9.4 billion.
Catchment from where water is captured and stored or recharged,
Conveyance system that carries the water harvested from the catchment to the storage/recharge zone,
First flush that is used to flush out the first spell of rain,
Filter used to remove pollutants,
Storage tanks and/or various recharge structures.
WHY DO RWH?
Rain may soon be the only source of clean water. Rainwater harvesting systems use the principle of conserving rainwater where it falls and have the following benefits:
Helps meet ever increasing demand of water
Improves quality and quantity of groundwater
Individual homes • Colonies • Apartments • Institutions Schools/colleges/universities • Clubs • Hospitals • Industries
Slums, everywhere. The potential for RWH is huge!
Setting up a rainwater harvesting is not difficult but requires some sort of understanding of hydrology and architecture and as a result most people find it too complicated to do it themselves. In order to make it simple and convenient for everyone to set up a rainwater harvesting system suitable for their needs, the Centre for Science and Environment has prepared a set of guidelines which will help you to set up your own rainwater harvesting system quickly and efficiently. Log on to http://cseindia.org/ to learn more.