Humans are using up groundwater—or water stored in naturally occurring aquifers underground—at a dangerous pace. Kellogg Schwab, the Abel Wolman professor in water and public health at the Johns Hopkins Bloomberg School of Public Health, talks with Dr. Josh Sharfstein about why groundwater is being depleted so quickly, what needs to happen to ensure the world doesn’t run out of this precious resource, and how water conservation could bring people together across state and country borders.