Which Indian city will run out of water first?

Every summer, residents in Indian cities brace themselves for the dreaded combination of extreme heat and water shortage. This summer the biggest victim has been Chennai—but almost all big cities in the country are equally at risk. As India rapidly urbanizes, demand for water is increasing and supply is struggling to keep up. A combination of climate change, wasteful water policies and inadequate infrastructure could turn the water vulnerability into a full-blown crisis.

Urbanization in India is raising many challenges, but none are as critical as the provision of water. And, on many measures, this challenge is far from being entirely met. For a start, a significant portion of urban Indians lacks access to piped water. In 2015-16, according to data from the National Family Health Survey, 31% of urban households lacked access to piped water or public tap water—a proportion that has not decreased significantly for nearly two decades.

Even for the households with connections, their pipes are in danger of running dry because of dwindling water supply. One estimation of this is per capita water availability, which measures the total amount of water supplied in the country after adjusting for population. India’s per capita water availability is decreasing and is expected to continue to do so dramatically. For a country with a growing share of urban population, this will only add another stress point.

Since water is a state subject, the responsibility for sourcing and delivering water to urban households falls to dedicated water boards (for example, the Delhi Jal Board) or municipal corporations. These entities typically source water from a combination of groundwater and surface water sources (dams, reservoirs and lakes). Natural sources of water, though, are susceptible to changes in nature—especially because of climate change.

Across India, climate change is disrupting the quantity and frequency of rainfall. A deficient monsoon can mean reservoirs struggle to fill up and less water seeps into the ground (especially in areas with significant urban construction). There is no data on water levels in all reservoirs that supply India’s cities, but in the 91 important reservoirs that the Central Water Commission tracks, storage levels have never crossed more than half their total capacity in the past five years.

Out of the top 10 most populous cities in India, the depth to groundwater (a measure of groundwater availability) in seven has increased significantly over the last two decades. Greater depths imply more difficulty in reaching water, and in Delhi, Bengaluru and Ahmedabad depths have nearly doubled.

This combination of groundwater and surface water depletion is a global phenomenon. According to a 2014 study, one in four cities in the world are water-stressed, places where the ratio of water usage to availability is greater than 40%. Within this list of cities with populations greater than 750,000, Indian cities fare especially poorly—24 of the 35 Indian cities in the list are water-stressed. These include all the metros and smaller cities such as Ahmedabad, Jaipur and Bhopal.

All these cities are expected to grow significantly and, as their residents get richer, they will also change how they use water (for example, using showers and washing machines), which will further strain water resources.

For a few of these cities, the combination of increasing water demand and climate change could be a particularly potent threat. In a 2018 study published in Nature, scientists Martina Flörke and others quantified the effects of urbanization and climate change on water scarcity across global cities. They found that by 2050, Jaipur will be the city with the second-largest water deficit in the world, Jodhpur the 14th most water-stressed and Chennai the 20th most water- stressed.

Click here to expand chart

Water shortages have many costs ranging from health to economics, but it is the poor who will inevitably suffer the most. Richer Indians complement inadequate public water supply with their own private sources (such as private borewells), but the poor cannot afford such luxuries. In Chennai, for instance, one estimate placed the costs of procuring water from a different source during droughts at around 15% of a poor household’s income.

Water shortages though are not the only problem facing India’s cities. Because of climate change and extreme rainfall, some cities can even suffer from excess water in the form of floods.

One common factor across both these water challenges is poor infrastructure. When it does rain heavily, water is not stored effectively. And, whatever water that is captured isn’t delivered efficiently.

The 2016-17 Economic Survey of Delhi estimated that the national capital loses 40% of its drinking water supply while it is being distributed. This is partly the result of poor infrastructure (such as leaking pipes) and water theft. As with power, theft and non-payment of dues severely constrain the performance of utilities across India.

Addressing these challenges will require improved water management. The first step towards this in cities is better data. Currently, there is a dearth of up-to-date data on water supply and demand at a disaggregated city-level. The NITI Aayog partially sought to address this through a Composite Water Management Index, but its indicators have been criticized by experts and even those within the government.

The water management index is questionable, and the Central Ground Water Board is drafting a fresh report on city-level demand, one person with direct knowledge of the matter said, on condition of anonymity.

Ultimately though, the most cost-effective solution to India’s urban water crisis may actually come from its villages. Agriculture demands the bulk of water in the country and, hence, savings in rural India could transform city water supply. In their study, Flörke and her co-authors argue that just a 10% increase in irrigation efficiency worldwide can help 236 million urban residents overcome water deficits in the future.

This is the third of a five-part data journalism series on India’s environmental crisis.