India faces significant water stress, a challenge increasingly compounded by the rise in weather extremes linked to climate change. According to data from the World Bank, the country has 18% of the world's population but only 4% of its water resources. Adding to this woe is the rapid rise in temperatures across the country, with temperature shocks or random fluctuations leading to soaring temperatures. These factors have adversely affected people from low-income groups, especially those without access to clean water.
A new study from the Indian Institute of Technology (IIT) Madras explored how extra hot days, the ones we call temperature shocks, are directly linked to household water poverty, a measure of how much access a household has to clean drinking water across India. Researchers wanted to better understand this connection, going beyond looking at big-picture water resources to see how climate change affects water access at the family level.
Surprisingly, regions in India with a history of wild temperature swings are better at handling current heatwaves and water stress. |
They used data from the India Human Development Survey (IHDS), which interviewed tens of thousands of households across India in two different time periods (2004-2005 and 2011-2012). This survey provided details about families' lives, including their income, education, and the number of people living in the house. It also provided the information needed to determine how water-poor each household was.
Water poverty does not mean having no access to water. To measure the access to water more accurately, the researchers used seven different factors: where families get their water, whether they have proper sanitation, how reliable the water supply is, how long it takes to fetch water, whether they treat their water to make it safe, whether they have storage, and whether they have enough water for their daily needs. They combined these factors into a score, where a higher score means more water poverty.
Next, they needed to connect this to the weather. They got climate data from 1970 to 2011 from the India Meteorological Department (IMD). This data included daily temperatures and rainfall for different districts across India. To figure out the temperature shock for a specific district in a specific year, they focused on how many days were unusually hot compared to the long-term average for that district.
They created different bins or ranges of temperature, like 9-12°C, 13-15°C, and so on, all the way up to days hotter than 33°C. Their primary measure of temperature shock was counting the days that fell into each hot temperature bin in a given year. By combining the household data and the climate data, the researchers could then use statistical models to see if there was a relationship between the number of hot days a district experienced and the water poverty levels of the households in that district.
The study found a clear link: more days in those hotter temperature bins significantly increased household water poverty. The hotter the bin, the bigger the impact. Days above 9°C started to show an effect, but the impact became much more pronounced for days above 33°C. Even small increases in the water poverty score, from 0 to 1, can mean significant hardship for families when they add up over days, months, or years.
They also measured each district's historical temperature variability to know how much the temperature varied over many years. Then, they looked at how the impact of a current temperature shock differed depending on that historical variability. Surprisingly, they found that regions with a history of more temperature variability were less affected by current temperature shocks. The researchers suggest this might be because communities in historically variable areas have already developed adaptive strategies. They may have invested in better water storage like rainwater harvesting tanks, found alternative water sources like wells or piped networks, or developed community systems to manage water during tough times.
More rainfall, as expected, generally helps reduce water poverty. Household income and education also played a big role: wealthier and more educated households tended to have lower water poverty, likely because they could afford better access or have more knowledge about managing resources. Conversely, households with more dependents (like young children or elderly relatives) faced higher water poverty, possibly because they needed more water but might have fewer working adults to fetch it or earn income. They also found that urban households generally had lower water poverty than rural ones, perhaps due to better infrastructure. However, urban areas still face their own water challenges, like ageing pipes and high demand.
This research is one of the first to use detailed survey data to examine how temperature shocks affect household-level water poverty in India. It also breaks new ground by showing that a region's history of climate variability can help buffer the impact of current heat waves. This means policies should focus on helping communities, particularly areas with less historical variability, develop better ways to manage water during heat waves. Investing in things like rainwater harvesting, improving local water infrastructure, and supporting families with resources to adopt water-saving technologies are key steps. Ultimately, this research underscores the urgent need to address climate change and ensure that every household, regardless of where they live or their history with extreme weather, has access to safe and reliable water.
This research article was written with the help of generative AI and edited by an editor at Research Matters.