Chennai’s Future Water Shortages Tied To Reuse Strategies
Rising urban and agricultural demand in the Chennai Basin could be mitigated through strategic reuse of treated wastewater, according to a new urban resilience assessment. The study warns that without interventions, population growth and climate pressures may leave hundreds of millions of cubic metres of water unmet by 2050, impacting both households and farms.
The basin, spanning Chennai, Chengalpattu, Kancheepuram, Tiruvallur and Ranipet districts, is projected to see water demand reach nearly 2,940 million cubic metres under a high-growth scenario. Urban planners and water experts emphasise that conventional supply approaches alone are unlikely to satisfy this surge, necessitating integrated, circular water management practices. Research highlights that combining micro-irrigation techniques with reuse of treated used water (TUW) can significantly reduce unmet demand. Modelling shows that scaling TUW reuse to 25–40% of total treated volumes, alongside targeted micro-irrigation, could cut shortfalls by over half by mid-century. Factoring in climate-adaptive interventions, the potential reduction in unmet demand rises to nearly 93%, underscoring the impact of coordinated water management.
Certain sub-basins, notably Kosasthalaiyar and Adyar, face disproportionate risk. Analysts suggest decentralised modular wastewater treatment plants near high-demand zones could enable non-potable reuse for industrial and domestic purposes, while also recharging groundwater. Such approaches align with climate-resilient urban planning by reducing pressure on freshwater sources and enhancing local water security. Currently, Chennai operates a network of 12 sewage treatment plants, with a combined capacity of around 934 million litres per day. While a fraction of treated water is released to recharge bodies like Porur Lake, the majority enters rivers, representing a missed opportunity for local reuse and demand management. Experts note that increasing reuse efficiency could support agriculture, urban landscaping, and industrial operations without stressing potable water supplies.
The economic and environmental stakes are high. Water shortages could affect industrial output, real estate development, and everyday livelihoods, particularly in densely populated and peri-urban areas. Strategically deploying treated water and micro-irrigation infrastructure not only reduces unmet demand but strengthens Chennai’s resilience against climate variability and population growth. Looking forward, city authorities and developers are urged to integrate TUW reuse into broader water planning, prioritising high-risk sub-basins and promoting modular treatment systems. Combining local reuse with smart irrigation could reshape Chennai’s urban water landscape, reducing reliance on rivers and reservoirs while supporting sustainable growth.
