Photograph of a Taanka: traditional rainwater harvesting tank, in Rajasthan, IndiaThis photograph of a Taanka (as it is called in Hindi) or rainwater collection tank, was taken near the town of Sujangarh in Rajasthan, India (in November 2008). This region of (north-west) Rajasthan usually receives scanty rainfall and has saline groundwater. Therefore, people here have been surviving on harvested rainwater for centuries, a lot of which is collected though Taankas and used judiciously in the months following Monsoon rains.

This particular Taanka had a small cemented (catchment) area around it, sloping inwards (towards the round tank). The tank, with a dome-like roof, had an opening on top to draw the collected water out, just like from a well.

Taankas stand as a reminder of traditional, cost effective, time-tested, simple and sustainable rainwater harvesting techniques that have been prevalent in India. It’s a pity that despite their existence, little or no effort to collect rainwater is made locally in India’s towns and cities where availability of water is usually stretched, and despite exorbitant spends on buildings, equipping them with expensive gadgets and digging expensive borewells. A concise writeup about Taanka on Wikipedia is worth reading.

The photographs above were taken in the city of Jaipur, India (in 2007 and 2006, respectively). The one on the left is of a thick stone wall from Jaipur’s historic walled city, the one on the right is of a conglomerate rock located inside a city park. One major difference between these two is of age, the wall is less than 300 years old whereas the rock is estimated to be about 1600 million years old (yes!). Many (man-made) walls and structures in the historic Jaipur walled city are in a state of decay, some have crumbled, yet the rocks in the nearby Aravalli hills look as good as new! Isn’t nature’s ability to maintain or sustain itself amazing?

This graphic attempts to illustrate what can potentially be done with one (A4) sheet of paper. For most uses mentioned here, the available real estate is double (the other side as well). And we should remember that saving paper = saving trees 🙂