An estimated one-third of the world's population will suffer from chronic water shortage by the year 2025 due to increasing demand for drinking water caused by growing population, decreasing quality of the water resulting from pollution and augmenting requirements of expanding industries and agriculture. The shortage will be particularly felt by people in arid areas and by rapidly growing coastal populations and mega-cities.

The increasing water scarcity, combined with its deteriorating quality, will have far reaching global impacts on human health, socioeconomic development potential of affected countries, freshwater and marine resources and biodiversity and may cause international conflicts over water rights. Pollution of freshwater is escalating throughout the world, affecting in many places the quality of drinking water and the integrity of freshwater and coastal marine ecosystems.

The freshwater hydrological cycles are inseparably linked with marine systems and the problems besetting river basins have profound impact on coastal and marine environment. Pollution from land-based sources is currently the most imminent problem affecting the aquatic biological resources and biodiversity. Coastal ecosystems, particularly those of small island developing states, are at special risk.

From the United Nations Environment Program.