Kolkata is India’s third largest city, located in the broader region of coastal Bengal along one of the key tributaries of the Ganges, the Hooghly River. Freshwater sources are abundant in the city’s immediate surroundings. The Hooghly itself forms the city’s Western boundary, running along its entire length. On the other side, the East Kolkata Wetlands is a massive social and ecological system of freshwater ponds that serves as the city’s primary wastewater treatment facility. Underground, a substantial aquifer lies beneath a thick confining bed, with a number of shallow unconfined groundwater sources located throughout the city.
There is no physical reason for the city to struggle to provide water to its residents, yet it is currently facing what many have called a water crisis. The municipal water supply is limited, of low quality and unreliable. Meanwhile, over-reliance on groundwater is causing rapid subsidence and contamination of the confined aquifer. In a low-lying city already considered at high risk from sea level rise, subsidence poses a serious threat to the future. I propose expanding the coverage area of municipally-provided treated surface water to reduce groundwater usage and build a broader foundation of potential rate-paying consumers.
Photo credit: Evan Tims. East Kolkata Wetlands, 2024.
Kolkata’s Water Challenge
Most of the city’s drinking water is drawn from the Hooghly River and treated at the Indira Gandhi Water Treatment Plant located in Palta, upstream of the city. This source serves consumers located in the area shaded in blue in figure 1. The second largest source of surface water is treated at the Garden Reach Water Treatment Plant, which provisions the region shaded in green, though some water at this facility is also drawn from municipal tube wells. The red zones represent groundwater-only supplied areas. However, even though these areas appear to be clearly demarcated, there are countless tube wells throughout even the surface-water supplied areas, contributing heavily to subsidence.
Figure 1. Source: Kolkata Municipal Corporation
There is a major gap between the water provided from these two surface sources and the water consumed by the city. Around 35% of the city’s population does not have access to any Kolkata Municipal Corporation (KMC)-provided piped water at all. Even in the central areas of the city, water does not flow through the pipes 24/7, instead sitting idle at low pressure for many hours, leading to the incursion of contaminants and water lost to leakage. Many homes and neighborhoods rely on rooftop tanks to source water during hours with no service. Countless others, especially in housing developments, utilize tube wells–some permitted by the KMC, others illicit. The KMC system itself also relies on numerous tube wells to supplement its surface water sources. (Ray et al, 2016). As a result, the city relies heavily on its confined aquifer despite the presence of a major river and wetlands.
Due to the over-reliance on groundwater, the city faces a subsidence crisis. According to the SwitchON Foundation, subsidence ranges from 1.13 to 43.8 millimeters per year in different parts of the city (Kapuria, 2024). Additionally, a massive groundwater trough has begun to form beneath the areas of the city most dependent on groundwater. Being confined beneath a thick clay bed, the city’s aquifer is not easily recharged. Instead, areas where the confining bed are thinnest also happen to be located in areas with high levels of pollutants. As a result, contaminants like sewage and arsenic are increasingly being drawn down into the confined aquifer (Sikdar et al, 2022). This poses a major threat to the long term safety of drinking water drawn from tube wells in the city. Thus, the city’s usage of groundwater is an urgent threat, not only due to the long term projected impacts of sea level rise but also the health and safety of drinking water in the city.
Photo credit: Evan Tims. Central Kolkata, 2019. The city already experiences periodic flooding during monsoon, especially in the low-lying neighborhoods of Central and North Kolkata.
Intervention: Increasing Coverage Area of Piped Surface Water
I argue that the city must focus on expanding its municipal network of water mains and pumps that supply surface water across the city, particularly to areas that currently rely most heavily on groundwater. Concurrently, the city should cease permitting new tube wells to housing developments and focus on connecting more neighborhoods and homes to central water mains. Entangled within this proposal are a number of legal, infrastructural, and economic challenges, but also a number of possible benefits.
Revisiting figure 1, I propose supplying water to the red zones from both surface water treatment facilities, followed by reducing groundwater usage in the green zone and ultimately throughout the city. This project would require two major infrastructural developments, namely expanding and building new water mains to these underserved areas, and building new pumping stations to maintain the flow of water through the pipes. Subsequently, an expanded service area would also require increased long term maintenance requirements, which I discuss in financial terms in the next section.
The clearest benefit to this intervention is reducing groundwater over-reliance. A certain amount of subsidence is “priced in” for at least the next decade, but slowing its rate and degree will be critical for securing the city’s future as it navigates sea level rise in the coming century. Another benefit is reducing the contamination of the city’s confined aquifer, so more sustainable usage of this resource would pose fewer health risks to consumers.
More broadly, creating a more thoroughly integrated system across the city would have several potential administrative and even financial benefits. Currently, the constant permitting of new tube wells for private housing developments has created a substantial population of water consumers separate from the municipal system. These residents also tend to be middle or upper class. Allowing tube well drilling is a means for the city to avoid taking on the expense and responsibility of creating and maintaining new water connections in these developments. However, I speculate that increasing the population of consumers reliant on the central system would also produce a public with a stronger vested interest in the quality and reliability of that system. Thus, connection to the central surface water system might lead to stronger political will to improve and expand water services, creating a sustainable social feedback loop that might produce more proactive water governance in the long run.
Figure 2: Bubble chart showing interlinked benefits of improving surface water coverage
Financing and Implementation: Costs and Benefits
The biggest hurdle to achieving a comprehensive supply of piped surface water across Kolkata is financial. The KMC water department has a limited budget and little independent revenue, as it does not collect consumer water fees. Instead, the KMC is funded primarily through the statewide budget (KMC) and several ongoing loans from the World Bank and the Asian Development Bank intended for infrastructural maintenance and improvement (Majumdar, 2017).
Building new water mains and at least several new booster pumping stations to service the groundwater-fed zones would be a significant upfront expense for a water supplier already underfunded and in debt. Further, with an expanded network tied into the centralized water system comes increased yearly maintenance costs, adding on to a budget stretched thin by the existing limited network.
Finding solutions for the KMC’s budget is beyond the scope of this post, but I do make several suggestions. First, I would reiterate that many new tube wells are being sunk by private housing developments inhabited by middle and upper-class residents, both for independent water supply and to supplement the lack of 24/7 piped surface water. West Bengal’s current state constitution defines water as a human right available free of charge, preventing the city from implementing consumer fees. However, the KMC’s website does lay out a system of fees applicable to large scale or mixed-use buildings, suggesting that there are avenues through which private housing developments might be sources of revenue without charging individual consumers per se. Given that fact alone, linking private developments to existing water supply instead of permitting new tube wells is a case for collecting sustainable revenue. Further, the state has previously reconsidered the idea of charging consumer fees, most recently in 2003 (Kapuria, 2024). If this was revisited, a large consumer base of middle-class residents in housing developments would A) be a strong source of revenue and B) be a more equitable and perhaps politically permissible target for fee collection. Linking these consumers to the physical water supply network, however, is the first step toward realizing that financial potential, rather than permitting most new developments to simply build new tube wells.
As a component of the Asian Development Bank (ADB) loan to the KMC, the city agreed to install water meters for individual residences, an effort that remains ongoing (Majumdar, 2017). Ostensibly, these meters are meant to monitor the availability of water in different areas to identify possible leaks and create a more accurate water provisioning system. However, the emphasis on individual residences, and the fact that this project emerged from negotiations with the ADB, indicates that charging consumer water fees to residents, or least having the infrastructural capacity to do so, is likely an aim under consideration. Given this context, I believe expanding the piped network to incorporate more middle and upper class developments dovetails with the goal of creating sustainable fee-based revenue, even if this is largely subtextual at the moment. Thus, re-allocating some funds from existing loans with the argument that expanding the network improves the infrastructure for future rate-paying consumers is one idea that could be explored.
Photo credit: Evan Tims. Hooghly River, 2024.
Conclusion: Prioritizing Resilience
There are significant hurdles to expanding the coverage of Kolkata’s piped surface water. However, the costs of failing to do so are potentially fatal for the low-lying coastal city. The Hooghly River is tidal, and much of the city already lies at a lower elevation than its banks. A system of gates prevents inflow into the city’s canals, but even the lowest sea level rise scenarios threaten to inundate portions of the metropolis. The entire region of coastal Bengal is considered among the most climate-vulnerable places on Earth, and Kolkata is no exception.
The growing threat of sea level rise cannot be ignored, nor can the contamination of the city’s aquifer. Luckily, the city is rich with potential sources and solutions. Unlike other South Asian cities, physical water scarcity is not an issue. If surface water can be adequately provided to all areas of the city, subsidence can be significantly reduced. This intervention does pose numerous financial and infrastructural challenges, and it cannot happen overnight. However, slowing subsidence and expanding coverage of surface water is essential to securing the future livability of Kolkata, one of the largest and most culturally significant cities in the world.
Photo credit: Evan Tims, 2023. A park in Central Kolkata with a temporary pond due to rainfall.
Sources:
Banerjee, S., Sikdar, P.K. Hydrochemical fingerprinting and effects of urbanisation on the water quality dynamics of the Quaternary aquifer of south Bengal Basin, India. Environ Earth Sci 81, 134 (2022). https://doi.org/10.1007/s12665-022-10258-3
Preeti Kapuria. “Valuing Water for a Smart and Sustainable City: Lessons from Kolkata.” Orfonline.org, OBSERVER RESEARCH FOUNDATION ( ORF ), 21 Aug. 2023, www.orfonline.org/research/valuing-water-for-a-smart-and-sustainable-city-lessons-from-kolkata. Accessed 3 Nov. 2024.
Majumdar, Arkamoy Dutta. “Kolkata Municipal Body to Meter Household Water Consumption under ADB Pressure.” Mint, 10 Jan. 2017, www.livemint.com/Politics/KFwcCgu1MR6bgbXt2qR99O/Kolkata-municipal-body-to-meter-household-water-consumption.html. Accessed 3 Nov. 2024.
Ray, Bhaswati, and Rajib Shaw. “Water Stress in the Megacity of Kolkata, India, and Its Implications for Urban Resilience.” Urban Disasters and Resilience in Asia, edited by Rajib Shaw et al., Butterworth-Heinemann, 2016, pp. 317–36. ScienceDirect, https://doi.org/10.1016/B978-0-12-802169-9.00020-3.
KMC. “Official Website of Kolkata Municipal Corporation.” Kmcgov.in, 2024, www.kmcgov.in/KMCPortal/jsp/WaterConnection.jsp. Accessed 3 Nov. 2024.