In theory, there is enough fresh water on Earth to meet increasing human needs. In practice, this may not be the case.
Water problems pervade many of our environmental concerns.
Of the latter, about 27 per cent is in glaciers and 72 per cent is underground. Less than one per cent of the world's fresh water, therefore, is to be found in the atmosphere, rivers and streams, and lakes. As both the world's population and usable water are unevenly distributed, the local availability of water varies widely. Much of the Middle East and North Africa, as well as parts of Central America and the western United States, are already short of water. Demand for water varies greatly in different countries, depending on population and the prevailing level and pattern of socio-economic development.