Since the beginning of time, water has been shaping the face of the Earth, not only as a geologic agent, cutting valleys and canyons and sculpting rock formations, but also as a major factor in the rise and fall of great civilizations and as a source of conflict and tension between nations. All of these civilizations built large irrigation systems and made the land productive. By the same token, civilizations collapsed when water supplies failed or were improperly managed. The decline of the Sumerian civilization of Mesopotamia, for example, is believed to be due to poor irrigation practices resulting in salt build-up in the soil. Similarly, the abandonment of Roman aqueducts, canals and reservoirs in North Africa helped return the region to desert condition.
Water sustains human life, it sustains our environment, and it sustains our cultures.
But the global demand for water is increasing and the destruction of water-dependent ecosystems has accelerated. Rapid population growth in developing countries is contributing to critical environmental degradation and this degradation, along with inadequate water supply and sanitation services, are imposing large health problems and burdensome economic costs on the poor. Water supply sources are being stretched to their limits, and many parts of the world are facing water scarcity. Sanitation facilities are either lacking or are being overloaded, and surface- and groundwater pollution is increasing rapidly. Over 1 billion people still do not have access to safe water supplies and over 1.7 billion do not have access to adequate sanitation facilities.