Bangalore water supply

Water and a City: Institutions, community and citizens at work in Bengaluru

By: S Vishwanath, The author is a Civil Engineer and Urban Planner.
Presently, the Cauvery River is the city’s sole water source located at a distance of 100 km. But with a population expected to reach 20 million by 2031, the rising demand for water presents unique challenges, calling for participation at all levels.
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The Context

The city of Bengaluru sits on a high ridgeline, 900 m above the sea level. With a population of around 11 million in 2017, the city is facing challenges in meeting its current and future water needs (Times of India, 2018). For now, the main water source is Cauvery, located at a distance of 100 km and around 300 m below the city level. Around 1400 million litres are pumped into the city every day, making it one of the highest energy consuming water projects and also one of the costliest in India (BWSSB, undated). Another 775 million litres per day is to come in when the Cauvery stage V project is completed but that will be all that can be drawn from the Cauvery (Lalitha, 2016). The project is expected to be commissioned by 2023 (Times of India, 2018). However, the city still grows. How then will water be managed for a growing city expected to reach 20 million by 2031 as per the Draft Revised Master Plan? According to the Draft Revised Master Plan prepared for the Bangalore Water Supply and Sewerage Board (BWSSB) the city envisages a three-pronged plan— reducing non-revenue water (water that has been produced and is ‘lost’ before it reaches the customer) from 49 to 15 per cent; enhancing rainwater harvesting; and reusing wastewater and enabling recycling.

Bangalore water supply – The Policy Framework

Reducing non-revenue water: It is a complex institutional task, which is currently being undertaken by the BWSSB with the aid of competent consultancies and contractors. It is reported (The Hindu, 2017) that the non-revenue water has already started to come down to 32 per cent or thereabouts.

Waste-water reuse and recycling: 28 waste water treatment plants will be put in place to treat 1400 million litres of sewage. This will become a resource to fill lakes, for industries and for non-potable use and will also be available for irrigation in adjoining farm lands.

Rainwater harvesting: The BWSSB has enacted a bye-law (Department of Parliamentary Affairs, 2009) in 2009 which makes it mandatory for all new buildings beyond a certain dimension to harvest rainwater. The law is simple—it states that any building on a plot larger than or equal to 120 sq m has to make provisions for storing or recharging 20 litres for every sq m of roof area and 10 litres for every sq m of paved area. The recharge structure should be a minimum of 3 m in depth. This has resulted in an increasing participation of citizens, innovators and livelihood seekers in the water solutions space.

Based on calculations from IMD data, with an average rainfall of 970 mm spread over 60 rainy days, it is possible to harvest nearly 90,000 litres in a year. While the policy mandates a minimum of 3 m depth for recharge wells, it is advisable achieve a depth of 6-9 m to enable more rainwater to be recharged. Many buildings are placing rain barrels—simple high-density polyethylene (HDPE) tanks, connecting them to rooftop runoff and collecting this for non-potable use. In 2017, the BWSSB reported that 72,000 buildings had complied with the bye-law as against 117,000 buildings which needed to do so (Bhardwaj, 2017).

Groundwater, Aquifers, Storage and Livelihoods

Bengaluru for long was a region of tanks and wells. The tanks storing water for irrigation are recharging the aquifer at the same time. The wells would be located surrounding the tank and this earth filtered water would be used for drinking and cooking. A total of 262 tanks were recorded by the Lakshman Rau committee (Chandra, 2015). The wells were however not counted but were approximated to be around 10,000 by the experts. One has only to go to the adjacent Kolar District to perceive how the erstwhile Bengaluru may have been before urbanisation took over.

In 1895, the city ran its first urban water supply scheme from Hessarghatta on the Arkavathy river (Subramanian, 1985). Slowly the tanks started diminishing in importance and with them the wells. Between 1982 and 1984, continuous drought for three years meant many wells ran dry. This was also the era of the advent of borewells. People went deeper for water and gradually borewell supplemented the well as a source of water, especially for construction purpose and then for domestic use. The city now has an estimated 400,000 borewells as per a study by the Institute of Social and Economic Change (Raju, Manasi and Latha, 2008).

Hessarghatta on the Arkavathy river

Bangalore water supply – Citizen’s participation

For Balasubramanian ‘Baloo’ Sastry, it is a ritual that cannot be missed. Along with his granddaughter, the young at heart 81-year-old will walk to his open well, located in the suburb of Vidyaranyapura and measure the increase or decrease in water level every day at seven in the morning. The well is 4 ft in diameter and 40 ft in depth. He has rigged up a float and a wire and on a rainy day has seen the water level come up by several feet. He takes particular pride in the rainwater harvesting system that he has rigged to recharge his well. All of the rooftop is connected via a blue drum filter filled with sand and charcoal. The rainwater then falls into the well  like a waterfall. Unlike the piped supply from the Cauvery, the water from the well has to be pumped up 40 ft only. For him, this makes it the cheapest water in town at INR 1 per litre with the lowest embodied energy and carbon footprint. In a pinch, even where there is a power cut, water can be hauled using the traditional rope, bucket  and pulley.

Further down is Cubbon Park, the lungs of the city. Here in the vast sprawling gardens are seven wells, each with 20 ft of water. If the wells are revived in 2018, about 65,000 litres can be supplied to the Park on a daily basis from the shallow aquifer. This too is easily recharged.

In the North of the city stands the Mahatma Gandhi Institute of Renewable Energy Development (MGIRED), located next to the Rachenahalli Lake. The well in their premise has a turtle swimming in it, a tradition with the old wells in the city. The crystal-clear water meets most of the water requirement of the campus. A citizen group, ‘Jalamitra’ adopted the lake in 2017, leading to its rejuvenation.

Interestingly, there is one section among Bengaluru’s residents who have not been seen participating in the city’s water security solution. This community, the Mannu Vaddar, holds a repository of knowledge, being the traditional well diggers. Even today, they are found going from house to house, looking for wells to clean. With encyclopedic insights about localities where open wells exist—Palace Orchards, Sadashivanagar, Shivajinagar, J.P.Nagar, Malleswaram, Rajajinagar, Yelahanka, Vidyaranyapura, Mathikere and so on. The community is an asset to the city. In the village Vaddarpalya near Sarjapura, more than 120 families of well diggers reside, whose inputs are rarely sought to help rejuvenate the city’s water resources.

Using traditional knowledge the Mannu Vaddar community can rejuvenate many disused open wells. Bringing the well diggers into the fold on mainstream water conservation will, however, require an incentivisation policy. While engaging at a personal level the author found that they are receptive about the art of rainwater harvesting and could easily connect rooftop rainwater into wells, thereby helping to increase aquifer levels. Recently, they helped recharge wells by linking them to storm water drains.

Through a process of engaging and training this community, giving recognition to their skills and knowledge, and ensuring livelihoods for them, the city can build its water resilience, harvest rainwater and bring back shallow aquifers to use.

The rehabilitation and rejuvenation of all the existing lakes in the city has been a long-standing demand of almost all citizens. Not only the lakes but the interlinking channels connecting them —rajakaluves, need to be cleared of encroachments and designed not as concrete basins and drains but as valleys and lakes. This will foster biodiversity and help infiltration of rain water, which in turn can enable ecological filtration of the water. The separation of untreated sewage and the elimination of solid waste from the lakes and rajakaluves needs a special focus. By designing a urban watershed for each lake to receive flood waters and then releasing it gradually to the connecting valley, much of the objectives of a clean environment and water self-sufficiency can be achieved. Also, of special significance is the need to expand the sewage networks and sewage treatment plants than what is being undertaken currently.

Similarly, fishermen play a key role in freeing lakes from water hyacinths and other weeds. A partnership with them will help clean lakes as well as augment their livelihoods, providing food to winged visitors to the city at the same time.

It is high time, therefore, to adopt an integrated approach to water management, harnessing the benefits of rain, lakes, wells and treated wastewater for the water security of Bengaluru. This will bring ecological, environmental and social benefits that will help mitigate the threat posed by hanging climate change. Institutions and citizens need to gear up for the challenge. Livelihoods such as that of well diggers can easily be integrated with the water security requirements of the city through a combination of recharge wells and rainwater harvesting.

References

Bangalore Water Supply and Sewerage Board, undated. Cauvery Water Supply Scheme, Available at: https://bit.ly/2NH2VM7

Bhardwaj Aditya K.V., 2017. Bengaluru fails to harness rain water even amidst crisis, The Hindu, June 8.

Department of Parliamentary Affairs, 2009. The Bangalore Water Supply and Sewerage (Amendment) Act, 2009, Available at: https://bit.ly/2ummnoI

Lalitha S., 2016. Cauvery Stage V project pipeline work given green signal, The New Indian Express, December 17.

Subramanian, D.K., 1985. Bangalore City’s Water Supply – A Study and Analysis, in Vinod Vyasalu and Amulya Kumar N. Reddy (eds.), Essays on Bangalore, 4: 51-104.

Raju KV., Manasi S., Latha N., 2008. Emerging Ground Water Crisis in Urban Areas – A case study of Ward No. 39, Bangalore City, Working paper 196, [Accessed from: http://www.isec.ac.in/WP%20-%20196.pdf]

Chandra S., 2015. Citing Rau panel report, govt may be barking up wrong tree, Deccan Herald, May 7.

The Hindu, 2017. BWSSB does a plan to rethink as plan to cut water loss flops, The Hindu, September 10.

The Times of India, 2018. With population booming, SC relief may not slake city’s thirst, The Times of India, February 17.

________________, 2018. Is Day Zero on the horizon? Taps could run dry in Bengaluru, Pune, The Times of India, March 23.

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