In our daily lives, we may just turn the shower on and flush the toilet down – and not think about the journey of the water to our shower or from our toilet. However, all of us know that terrible plight when the tap goes dry.
We must keep reminding ourselves that the ultimate source of our water is rain. And so in any place we live, the water that is native to it, the water that was meant for it, is the water the rains bring. Bengaluru receives an average of around 970mm of rainfall – this is bountiful rainfall. In Bengaluru, it is also well distributed – two rainy seasons (the pre-monsoon and the monsoon) spread across nearly six rainy months.
The average rainfall in Bengaluru looks something like this:
Traditionally, Bengaluru would catch much of its rain in a series of lakes – these lakes served to store the water for use and recharge groundwater so that wells would be full. Over time, we have not taken care of these lakes – we have encroached on them to convert them to real estate. We have been pumping more water from the River Kaveri – which is a 100km away and 300m below Bengaluru – to serve our needs. With our open wells drying up, we have been digging deeper and deeper to access more groundwater. And all our waste water has been polluting our lakes.
Bengaluru’s call on Kaveri water has now been capped – we have all read about it in our papers. We have all experienced the problems of our borewells running dry. Bengaluru’s thirst cannot be quenched only by relying on these two ways anymore. How then does Bengaluru begin to address its water challenges?
Bengaluru has to do a few new things: First – harvest Rainwater (and prevent urban flooding!). Second – make its waste water a resource – i.e. treat it well and reuse it. Third, understand and manage its ground water sources well, rather than simply extracting from it. Fourth manage its demand – ensure water is used wisely and not wastefully. If Bengaluru has to implement any of these, it can be achieved if and only if we citizens become a part of these solutions.
The Bangalore Water Supply and Sewerage Board (BWSSB) has taken the first step in the above solutions. Rainwater harvesting has been mandated by the building bye-laws in 2005. Rainwater harvesting has also been made mandatory (for all buildings of size 30ft*40ft and above) by the amendment of the BWSSB Act in 2010. This law also states that the rainwater harvesting system should be designed for a 20mm rainfall event – meaning that for all showers below or upto 20mm, all the rainwater in the house has to be either stored and used in the house or has to be recharged back into the ground to replenish our wells. For Bengaluru’s rainfall pattern, if this is followed, residents can ensure that 80% of the rain falling on their houses is utilised. For a 4-member household, living on a 30ft *40ft plot, this means it meets atleast 30% of their needs – assuming the needs are responsible (i.e. 135 Liters per person per day or less). It is for us citizens now to follow this law – it is now upto us to be a part of this solution.
And Bengaluru now has a growing body of experience in understanding and implementing rainwater harvesting. There are many individuals, institutions, apartments, layouts who have pioneered, solved problems in their local context and have demonstrated benefits for themselves. There are also efforts to share these experiences with others. We can all benefit from these efforts.
With every individual, community or institution I engage with or whose story of water harvesting I listen to, it is clear that what begins as an exploration into water harvesting, then becomes an understanding of the journey of water and how to better manage it.
Implementing Rainwater harvesting means asking critical questions such as: how much does it rain? how much water is one using?, what does good water quality mean?, how does a borewell work? And so on. All these are fundamental questions that reconnect us, citizens of Bengaluru, to the journey of water into our shower and out from our flush – a connection without which Bengaluru cannot solve its water woes. So let us look at the skies and harvest the rain, help our neighbour to do the same and share our story.
The Alternative is an online media publication focused on sustainable living and social impact.