Wednesday, May 25, 2005

Rainwater Harvesting

Treehugger reports on a rainwater harvesting workshop held in Toronto. Some important points were made here.

We assume that rain water harvesting is needed only in seriously water starved communities and areas. Those theories stand bunked. Here is why:
1. Even if a town is sitting right beside a giant fresh water lake, pumping the water out of the lake and into people's homes involves huge expenditure in the form of investment in infrastructure and the ongoing expenses in terms of personnel and power to keep that infrastructure running.
2. Rain water harvesting reduces the load on public drains - hence no water clogged roads and reduction in infrastructure and maintenance costs for urban infrastructure.
3. Rain water is usually safer to drink than the mains water supply in many cities. Even if you dont drink the rain water you can still use it for 95% of the needs - only 5% of the water is for drinking/cooking.

There is a difference between the kind of rain water harvesting (RWH) that is practised in the West and what it implies in India. In the West (it is actually most popular in Australia), you directly take the water falling on your roof and collect it in a giant tank - like in this example - to be reused whenever required. Works for regions where it rains little but through out the year. However, since most of the rainfall is concentrated in just 3-4 months in most regions in India, rain water harvesting for us usually refers to using the rain water to charge the water table or ground water level. So the water level in our wells, borewells, lakes and ponds rises, and we still have the other benefits of reducing strain on public infrastructure. And maybe some Karma too, who knows?