This month, water once again takes center stage at the 4th World Water Forum in Mexico City. It is an opportune moment: While much of the world's attention has been fixed on issues of energy supply and security, hundreds of millions of people in the developing world continue to see the supply and security of fresh water as equally, if not more, important.
Surveys undertaken by the World Bank in developing countries show that when poor people are asked to name the three most important concerns they face, "good health" is always mentioned. And a key determinant of whether they will have good health or not is access to clean water.
More than a billion people around the world today do not. As a result, they are increasingly vulnerable to poor health. The World Bank estimates that by 2035, as many as 3 billion people, almost all of them in developing countries, could live under conditions of severe water stress, especially if they happen to live in Africa, the Middle East or South Asia. This will cause obvious hardship, but it will also hold back the economic growth needed for millions of people to escape poverty.
In Latin America, about 15 percent of the population -- roughly 76 million people -- do not have access to safe water, and 116 million people do not have access to sanitation services. The figures are worse in Africa and parts of Asia.
This is a situation that few people in rich countries face. Generally, these countries' citizens enjoy services that provide for all water needs, from drinking to irrigation to sanitation. In addition, other water-related issues, such as the risks posed by flooding, have been reduced to manageable levels.
Rich nations have invested early and heavily in water infrastructure, institutions and management capacities. The result, beyond the health benefits for all, has been a proven record of economic growth; one only has to look at investment in hydropower to see the positive impact of water management projects on many economies.
Granted, rich countries have a certain advantage: They benefit from generally moderate climates, with regular rainfall and relatively low risks of drought and flooding. Even so, they are not immune to water-related disasters, as Hurricane Katrina's destruction of New Orleans taught us.
But the impact of such events on poor countries is much greater. Extreme rainfall variations, floods and droughts can have huge social and economic effects and result in the large-scale loss of life. The Gulf coast of Mexico and Central American countries have repeatedly experienced such tragedies, with poor communities the most vulnerable and the least able to cope.
Ethiopia and Yemen are equally stark examples. Ethiopia's development potential is closely tied to seasonal rains, so high rainfall variation, together with a lack of infrastructure, has undermined growth and perpetuated poverty. A single drought can cut growth potential by 10 percent over an extended period. Yemen, for its part, has no perennial surface water; its citizens depend entirely on rainfall, groundwater, and flash flooding.
To move forward, developing countries need new water infrastructure and better management. Any approach must be tailored to the circumstances of each country and the needs of its people, but there is no fundamental constraint to designing water development investments that ensure that local communities and the environment gain tangible and early benefits.