Water security is becoming an urgent global challenge. Hundreds of millions of people already live in water-scarce regions, and the UN projects that by 2030 about half the world’s population will be living in highly water-stressed areas. This will be a crisis even for developed countries like the U.S., where water managers in 40 states expect freshwater shortages within the next 10 years. As the global population and GDP grow, so will the demand for freshwater. And, with the continuing rise of global temperatures, water shortages will only get worse.