Hyderabad is facing a severe water crisis, with one of its main reservoirs at just 13% capacity and 6,000 water tankers being booked daily. However, Chennai's experience with rainwater harvesting may offer a solution. In 1995, Professor Sekhar Raghavan noticed that his tap water had turned salty due to falling groundwater levels allowing seawater to seep in. He began promoting rainwater harvesting, collecting rainwater from rooftops, driveways, and other surfaces, filtering it, and recharging underground aquifers. His efforts led to the Tamil Nadu government making rainwater harvesting mandatory in buildings in 2003, resulting in a reported 20-foot rise in groundwater levels and improved water security for Chennai. Despite this success, the city's systems were weakened by poor maintenance, clogged filters, and neglected recharge pits. Today, Chennai is exploring new solutions, such as sponge parks and underground rainwater capture systems, to strengthen its water resilience. The city's experience highlights the importance of maintaining and protecting groundwater and making every drop count. As Hyderabad faces mounting water stress, it may benefit from learning from Chennai's approach to rainwater harvesting.