This report is the most recent in a series of GAO reports examining the nexus between energy and water. The report looks at the vast amounts of water used by the U.S. in energy production, from cooling thermoelectric power plants to the growth of feedstocks for biofuel production to oil and gas extraction. It also examines how water and energy are inextricably linked in the treatment of drinking water and wastewater. The GAO report noted several factors likely to affect future supply and demand for both energy and water, including climate change, population growth, and demographic shifts.