On this episode of The Evidence, Claudia Hammond discusses all things hydration with a panel of experts. Where do our hydration guidelines come from? How do we determine the perfect amount of water we should drink? What are the issues with water access that people and populations face aroud the globe? And how will climate change affect the amount of water we need, and our access to it. In front of a live audience at the Wellcome Collection in London, Claudia discusses these questions and more with Neil Turner, nephrologist and professor emeritus at Edinburhg University, Yael Velleman, Director of Policy and Innovation at Unlimit Health, working at the intersection of water access, sanitation, and disease; and Anthony Acciavatti, an associate professor at Yale Architecture School and creator of the exhibtion Groundwater Earth: The World Before and After The Tubewell.