the oecd environmental outlook to oecd b projects that by the number of people living in areas affected by severe water stress will increase by another billion from the baseline to an estimated billion people of the world population mostly in nonoecd countries over the last century water use has increased sixfold while population has increased at only a half of that rate bergkamp and sadoff 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