Contaminated water can spread diseases like cholera and typhoid. A new project aims to provide water filters in the form of an educational book. Soe Than Win/AFP/Getty Images hide caption

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Current water-filtering technology is costly, but MIT scientists are testing a simpler and cheaper method that uses wood from white pine trees. Wikimedia Commons hide caption

itoggle caption Wikimedia Commons

Scientists published the first global survey of the known undersea freshwater reserves. Water is relatively cheap now, but the reserves could be valuable if it becomes scarcer in the future. Olivier Morin/AFP/Getty Images hide caption

itoggle caption Olivier Morin/AFP/Getty Images

Demonstrator China Starshine holds up signs outside of City Hall in Portland last week. Ross William Hamilton/The Oregonian/AP hide caption

itoggle caption Ross William Hamilton/The Oregonian/AP