Bengaluru today, your city tomorrow

Some years ago, at the release of our report Excreta Matters in Bengaluru, I got into a spirited discussion with the city’s water and sewage managers. The discussion was about water management in the city, which our research showed was unaffordable and so unsustainable. The engineers disagreed. According to them, they had managed to secure water from the Cauvery, some 100 km away, through pipelines, and so had no reason to worry. Now as this hi-tech city hurtles towards a severe water scarcity, maybe, just maybe, these wise men will reconsider and rework their options going forward.

The fact is, Bengaluru is just another city that is being shown the mirror—the dreams of a perfect water supply driven by high-cost engineering solutions are being shattered. And this is in an era of climate risk, where rainfall will become more extreme and more variable.

Bengaluru in the now-distant past used to receive water from its vast network of lakes, designed to collect rain and mitigate floods. Then the search expanded: its first official water supply was from Hesaraghatta lake on the Arkavathi river, 18-20 km from the city; and then from T G Halli reservoir, 35-40 km away. But all this did not suffice and around 1974, the ambitious Cauvery Water Supply Scheme was conceived—where water would be pumped up to a height of 490 metres and transported over 100 km. During my interactions with the city engineers, they were deep into stage 4 of this engineering marvel, and as I said, they did not see any reason to worry. I spoke about the cost of transporting water longer distances—about a decade ago, the city required huge power to pump the water, which was eating into the fragile economics of its water and sewerage board. Also, as the distance increased, so did the water loss which, according to official sources, was 40 per cent. All this meant that the cost of water supply was going up.

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I also pointed out that the engineers were discounting the following facts: one, groundwater usage was increasing in the city and its surrounding areas, which suggested that the water supply was not so perfect. Two, the city was exploding and this expanding water-sewage infrastructure would not keep pace with growth. Three, most importantly by their own admission, bulk of the sewage generated was not being treated and this in turn was adding to the pollution load in its lakes and streams. But again, the engineers were sanguine about the future. They boasted they had already built some 720 million litres per day (mld) of sewage treatment capacity, using every available technology possible—which technically would be able to treat almost all the sewage generated. When I pointed out that less than half the capacity was being utilised, they told me, very soon the pipeline network would expand and all would be well.

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Cut to present day. In 2010, the city’s water requirement was pegged at 1,125 mld, which has more than doubled to 2,600 mld. While the Cauvery still supplies half, the rest comes from groundwater. In other words, the demand has remained unmet and people have had no option but to dig and dig deeper to secure their water supply. With increased variability of rainfall, these sources are drying up, and fast. But the pipedream sellers have not understood the crisis—the city’s chief water manager is now banking on stage 5 of the Cauvery project, which, he says, will be commissioned very soon.

The sewage story is similar. New hardware for treatment has been built; according to the Central Pollution Control Board’s 2021 inventory, the city now has 1,167.50 mld of sewage treatment capacity. And capacity utilisation has also somewhat improved to 75 per cent. But the gap between the generation of sewage and treatment capacity has widened. With the current water demand, sewage generation would be close to 2,000 mld—and so untreated sewage would be more than half. The city has gone round in circles, only to find that it is still standing where it was a decade ago.

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This is the real crisis of our water planning—the inability to understand the need and the opportunity for the change. The fact is, Bengaluru receives enough rain; it has lakes that can harvest this rain and recharge groundwater, so that in times of extreme rain events, its rich and powerful denizens do not have to swim to avoid drowning in the flood. Every drop can be used for the coming period of scarcity. Then it can manage its sewage differently. Instead of believing that it can transport sewage with pipelines, it can ensure that every drop of excreta is collected by tankers and then treated and reused. But for this, water engineers have to come down to earth, rework and rethink. This is Bengaluru’s story today and your city’s story tomorrow.