Water security: India must boost wastewater reuse to tackle insecurity

In an attempt to reduce water waste, the Union government last week proposed regulations to mandate up to 50 per cent wastewater reuse by 2031 for bulk consumers. This is an important step towards mainstreaming the reuse of treated wastewater in the country and must be welcomed in a water-stressed country like India, which houses 18 per cent of the world’s population with only 4 per cent of global water resources. The NITI Aayog’s “Composite Water Management Index Report”, released in 2018, showed approximately 600 million people in the country experienced high to extreme water stress. Additionally, consumption of contaminated water is associated with 200,000 deaths annually. In this context, the proposed regulations will require entities consuming over 5,000 litres daily to register with authorities and implement comprehensive wastewater-treatment measures. This includes residential societies, institutional and commercial establishments, and industrial facilities.

A new report “State of Global Water Resources”, released recently by the World Meteorological Organization, has mapped recent trends and deserves attention. It noted that the year 2023 was marked by unprecedented heat, making it the hottest year on record. Compared to many other regions in the world, India performed well in terms of groundwater levels, terrestrial water storage, and soil moisture. However, it’s worth noting 2023 was the driest year for global rivers. This is evident from reservoirs receiving below normal water inflow in Australia, the Americas, and along the west coast of India. Besides, India experienced much above normal active evapotranspiration (AET) during March, April, and May last year. AET, one of the key elements in the hydrological cycle, refers to the process by which water is evaporated, encompassing evaporation from the soil or vegetation surface and transpiration from plants, and is responsible for a large part of the water loss from the soil.

Given the climate risks, India needs to prepare to deal with them because water stress is only likely to worsen. Research conducted by the Council on Energy, Environment, and Water (CEEW) suggests 11 of the 15 major river basins in India are expected to experience water stress by 2025. Five of these — the Ganga, Subarnarekha, Krishna, Mahi, and Tapi — have an annual per capita availability of less than 1,000 cubic metres per person. Three others — the Cauvery, Pennar, and Sabarmati — are facing water scarcity, with annual per capita availability of less than 500 cubic metres per person. Per capita availability of water has already fallen from around 5,000 cubic metres in 1950 to 1,486 cubic metres in 2021 and is set to decline further to 1,367 cubic metres by 2031. Lower availability of water will also affect the industrial sector and have implications for growth and development. Among industrial sectors, coal-based power plants and steelmakers remain the most vulnerable to water stress due to their heavy reliance on freshwater. However, despite the stress, only 28 per cent of sewage wastewater generated per day in ur­b­an centres in India is treated and reused. Reusing treated wastewater can not onl­y arrest growing water insecurity in the country but also reduce greenhouse gas emission, and contribute towards wetland restoration and river augmentation.