Red is for danger, and these maps reveal where the water crisis is biting hardest. We show country-by-country figures for the percentage of people with access to safe water. We reveal the percentage of the total disease burden for each country that is caused by unsafe water, poor sanitation and hygiene. It's not just drinking supplies that we need to be worried about: the pie charts (see Fig. 1) below show that water — clean or contaminated — will become an increasingly scarce commodity. Stress is defined as less than 1,700 m3 per person, per year. Scarcity means less than 1,000 m3 per person, per year. Research and text by Nature intern Hannah Hoag. We are grateful to Peter Gleick of the Pacific Institute for Studies in Development, Environment and Security, Oakland, California, for his assistance in collating these data. See http://www.nature.com/nature/focus/water for enhanced and extended graphics.

Figure 1
figure 1

SOURCE: R. ENGELMAN ET AL. PEOPLE IN THE BALANCE (POPULATION ACTION INTERNATIONAL, WASHINGTON DC, 2000)

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