The OECD Environmental Outlook to 2030 (OECD, 2008b) projects that by 2030 the number of people living in areas affected by severe water stress will increase by another 1 billion from the 2005 baseline to an estimated 3.9 billion people (47% of the world population), mostly in non-OECD countries. Over the last century, water use has increased six-fold while population has increased at only a half of that rate (Bergkamp and Sadoff, 2008). Changes in patterns of withdrawal from nature and consumption are therefore also a major part of the problem. While this may have partly resulted from policies that favoured more efficient water use and its decoupling from economic and population growth, in some countries demand has had to shrink in response to drought.