Towards circularity in used water management in India: mainstreaming reuse for its economic and market potential

Per capita renewable freshwater resources have been diminishing steadily over the years across the globe. India is no exception to the issue of water scarcity, with the problem being more severe in rapidly developing urban areas, where there is increasing pressure on existing freshwater resources to meet the growing water demand. In such typologies, the reuse of treated used water (TUW) is one intervention that has the potential to address the demand–supply gap and improve the water environment if managed properly. Using the nexus lens, this paper makes a case for mainstreaming domestic used water treatment and its reuse for non-potable purposes in India by estimating the market potential and direct (irrigation) and indirect (reduction in fertiliser consumption and greenhouse gas emissions) economic value of the reuse at the national scale. The overall daily market value of TUW was estimated at INR 630 million in 2021, which will substantially increase to over INR 1.9 billion by 2050 at the current market rate. Further, about INR 966 billion worth of revenue would have been generated by using TUW for irrigating crops in suburban areas in 2021. Further, reusing TUW for irrigation would lead to nexus gains in terms of reduced dependence on synthetic nutrients, groundwater and energy. The reductions in fertiliser use, on account of the nutrient content of TUW, and carbon emissions, due to less withdrawal of groundwater, would have been 6000 tonnes and 1.3 million tonnes, respectively. To realise these potentials, it is important to strengthen the existing governance on reuse, which would also enable a circular economy approach to used water management in India.