Urban Water


We all know how life on earth is inextricably linked to the presence of water; and access to water has been central to evolving civilisations. Isn’t it truly special then, that a landlocked city like Namma Bengaluru, with no perennial water source, has been a site for human settlement since the 9th century (likely even earlier), due to its unique system of interconnected tanks! These human-made tanks relied solely on rainwater and surface runoff from their catchment areas, (the regions where water collects and flows into the tanks). They were interconnected through a network of stormwater drains called kaluves, that transported the overflow of one tank into the next lower-elevation lakes; thereby effectively managing floods and conserving water

However, despite this long history that Bengaluru shares with water, adequate water supply for the growing city has always been a challenge, even back then. The failure of the monsoons and the Great Famine of 1875-77 led to almost all the tanks drying up. The city, though, continued to grow in size and population. Within a couple of decades (1905), Bengaluru became Asia’s first city to receive electricity. This meant that the city could now access water from distant sources. Hesarghatta, Thippagondanahalli reservoir and then the Cauvery river became our preferred sources of water. In time, as piped water became available to the city, our relationship and dependence on tanks, as a source of water, visibly reduced.

According to a recent report Bengaluru’s demand for water today is met primarily from groundwater – a fast depleting resource, the Cauvery river – nearly 100 km away, and only marginally from rainwater and treated wastewater. 

Despite several civic initiatives that have been working to rejuvenate some of Bengaluru’s tanks, it has not had the intended long-term and city-wide impact. This is because for Bengaluru, like all urban water systems, a lot depends on the hydrological context. A key factor being the unique location of the city on the ridge line between the Arkavathy river basin to the west and the Dakshina Pinakini to the east. Additionally the 3 different watersheds of the city also vary significantly in their flow, drainage and topography. Bengaluru is also subject to seasonal fluctuations; it receives rain between June and November from both the South-West and the North-East monsoons. And it has a history of convectional rainfall in the months of April-May. When considered together, these features affect the flow of water in the city, making the network of cascading active tanks, and their conservation and management, even more critical in addressing extremes of flooding or water scarcity.

In addition to these hydrological factors, the city’s rapid and unplanned growth has also contributed to today’s increasing reliance on groundwater. New residential layouts, high rise apartments and business parks typically lie outside the core zone and are not serviced by the city’s utility – the Bengaluru Water Supply and Sewerage Board. This means they depend heavily on tankers and private borewells since pipelines for Cauvery water have not yet reached these areas. On the other hand, for groups living in slums and low income areas, the challenges faced are at various levels. Often, the slums may be ‘undeclared’ – not recognised by the State, which means they do not have access to piped water infrastructure. More often than not, homes in low-income areas depend on erratic, shared water supply (for instance, public taps and/or borewells) which they use – unfiltered – for drinking, washing, cooking and everything else. Poor quality water and inadequate sanitation infrastructure further compounds the problem for the urban poor, leading to diarrhoea, malnutrition, stunted growth and other serious consequences for public health. Over the last decade, water ATMs have become another option for those living in low income areas but at Rs 5 for a 20 litre can, these are not affordable by everyone. Extreme weather events induced by climate change add another layer of complexity to the problem. In months of heat and drought, water scarcity leads people to access water from sources which are contaminated, as potable water becomes precious and expensive. Droughts also act as a factor for various air borne diseases. Dry, dusty conditions increase the number of particles suspended in air and also encourage the freshwater blooms of cyanobacteria. Conversely, with the onset of rain, improper drainage and water logging promotes suitable conditions for mosquitoes and flooding results in further contamination of water sources as well as physical spaces. 

Another key aspect of water management in Bengaluru is waste water. In its simplest definition, it means what we get after using water in any activity – be it domestic, industrial or commercial. While the term ‘waste water’ denotes a byproduct that cannot be used and is hence seen as ‘waste’, it is rapidly being accepted as one of the most important elements in meeting the water needs of growing populations across the globe.   

‘Waste water’ is often used interchangeably with sewage, but is not just sewage. Sewage refers to the water discharged after use, with all kinds of waste, including faeces; sewerage/sewers are the structures that the discharge goes into. Sullage, on the other hand, is the wastewater that arises from domestic activities such as washing in bathrooms and kitchens, including water from food preparation and dishwashing; it does not contain human excreta.

Bengaluru, a thriving metropolis and the hub of India’s IT industry, faces a significant challenge in managing its wastewater. The rapid pace of urbanisation, industrial growth, and population expansion has led to an exponential increase in the generation of wastewater. As this issue gains prominence, it becomes imperative to examine the challenges associated with wastewater management in Bangalore and explore sustainable solutions to ensure the city’s water security and environmental well-being. In the context of Bangalore, estimates put the total wastewater produced by the city at around 1950 MLD. Out of this, more than 63% is treated in centralised treatment plans and 13% by decentralised treatment plants, while 24% goes untreated. Of the treated wastewater, only 30% is reused. 

Several challenges complicate the effective management of wastewater in Bangalore. One of the primary issues is the inadequate sewerage infrastructure, resulting in the discharge of untreated sewage into water bodies. The industrial sector, too, contributes significantly to the problem, with many units releasing effluents without proper treatment. Encroachments on stormwater drains exacerbate the issue, leading to the contamination of both surface and groundwater. Perhaps, one of the most significant challenges concerning waste water is addressing the mindset that despite treatment, waste water is not usable. Advanced treatment processes, including membrane bioreactors, constructed wetlands, and decentralised wastewater treatment systems are in fact currently being deployed to treat wastewater in the city. The Koramangala-Challaghatta (KC) Valley project, in which the government plans to fill 134 lakes at the cost of Rs 1,342 crore is one of the first in India to formally use secondary treated wastewater at such large volumes to fill the tanks and river ecosystem and provide water for agricultural use. Several other initiatives, individuals, institutions and groups in the city are also trying to address the challenges related to waste water management.

The absence of a single body responsible for all aspects of water management in the city.  Consequently, accurate and reliable projections and planning are common issues. 

The good news is that despite all these issues, Bengaluru is also home to several individuals, organisations and institutions that have been working to address Bengaluru’s water challenges in a number of ways. Visit the BSF SGP Projects page to see the breadth of initiatives working on water in the city.

Putting it in perspective

  • Bengaluru draws from 2 river basins Cauvery-Vrishabhavathi-Arkavathy and Dakshina Pinakini
  • Estimated 1400 lakes in the 1800s. 194 remained in 2016. 33 living lakes now. 
  • There were estimated 1,960 open wells in the city at the turn of the last century. Now, down to 49. 
  • Annual rainfall approx 920-950 mm across 60 rainy days. Rainfall in Bengaluru in a normal year is equivalent to around 3,000 million litres per day, if averaged out over the entire year. In comparison, what is pumped into the city from the Cauvery 100 km away and 300 metres below is around 1,400 million litres per day. 
  • The last 3-4 years, rainfall  on average has been 1000-1200 mm per year with an intensity of 180mm/hr. Traditionally, our pipes and systems were designed for 60mm per hour
  • Only about 1/3rd of households in Bengaluru get piped water supply from BWSSB. The rest are dependent on borewells (14,700 borewells according to authorities).
  • Currently, the Bengaluru Water Supply and Sewerage Board (BWSSB) supplies 1,450 million litres of water per day (MLD)to the city. By 2031 Bengaluru’s population is projected to reach 20 million residents. The BWSSB plans to increase the water supply to 3,550 MLD to cater to this projected rise in population. The BWSSB also plans to recycle sewage water and add another 1.600 MLD of water for the city’s needs.
  • BWSSB Guideline for Rainwater Harvesting (RWH) Minimum Requirement: Rainwater storage (surface tank or underground sump) and ground recharge (RCC precast ring well) of minimum 20 liters per square meter of roof area and a minimum of 10 liters per square meter of paved open space provision shall be made.