T he recent severe drought in key US farming states has focused attention on water issues. While some observers worry primarily about rising food prices in the wake of droughts, others see the drought as evidence that freshwater scarcity is bound to be a major challenge of the twenty-first century. Almost one-fifth of the world's population currently suffers the consequences of water scarcity, and this number is expected to increase (World Water Assessment Programme 2009). Population growth, rising standards of living, and the diet and lifestyle changes they imply will continue to increase the demand for water and strain available water resources. Pollution may also challenge the fresh water that can be used. In addition, discussions of climate change and the implied disruptions of the hydrologic cycle have only heightened concerns about water scarcity. In spite of the reports about an impending water crisis, it is important to realize that major concerns about water availability stem especially from the very uneven global distribution of water. The world as a whole is not running out of water. For one, the hydrologic cycle of evaporation, condensation, and precipitation makes fresh water a finite, but renewable, global resource. In addition, there are enormous quantities of water available, on the order of trillions of gallons of water per capita.1 However, while many countries 1 See Young and Haveman (1985). Even though only a very small fraction of this amount is not salty and accessible, there is more than enough fresh water on earth to satisfy the growing demand, especially since water desalination is always an option, See Gleick (2009) and Richter (2012).