The Brihanmumbai Municipal Corporation (BMC) is undertaking a significant project to reinforce its century-old underground storm water arch drains in Mumbai, India, using innovative geopolymer lining trenchless technology. This initiative, which began in April 2023 with a budget of ₹535 crore (approximately $64 million USD), aims to extend the lifespan of these drains by at least 50 years and enhance their capacity to handle heavy rainfall. A survey conducted by experts from IIT Bombay and VJTI identified 56 damaged storm water arch drains spanning 23.58 kilometers, with 27 drains requiring urgent rehabilitation. The project is crucial as Mumbai has experienced intense rainfall in recent years, leading to severe flooding. The trenchless technology allows for repairs without extensive excavation, minimizing disruptions in the densely populated city. However, progress has been slow, with completion expected by November 2027. This modernization effort is part of BMC's broader strategy to improve the city's drainage infrastructure and mitigate flooding risks.