Water, water everywhere, not a drop to drink?

Excerpt

Many of the reported stories in the past several years about the growing shortage of fresh water in parts of the world are outright scary. Sources of fresh water in places in Africa, Asia and South America are fast running out owing to accelerated net extraction for human use. The problem is revealing itself even in the developed world. In the Millennium Development Goal¹ formulated at the UN Millennium Development Summit in 2000, lack of access to safe water by the world’s poor was pledged to be cut into half by 2015. Is the world fast approaching an impossible situation similar to what S.T. Coleridge described so poetically in his Rhyme of the Ancient Mariner? Can we overcome the impending crisis by developing affordable technologies for producing potable water from water polluted by either natural or anthropogenic causes? This is one of the great challenges of the 21st century. …