Polluted water kills 15 million children under five every year and affects the health of 1,200 million people. Water-borne diseases kill millions.
The United Nations today marks World Water Day with the theme "Water for Health". "The water crisis, unlike the energy crisis, is life threatening," said Mr Klaus Toepfer, executive director of the UN Environment Programme. "And it is the children and women who suffer most."
The negative impacts of unsustainable water use and pollution of watercourses result in harsh environmental, economic and social costs, according to the UN. Failure to dispose properly of human waste causes diseases such as cholera and dysentery which kill three million every year.
Inadequate water management promotes the spread of malaria, which kills another 1.5 million to 2.7 million people annually. "When the environment suffers, people suffer, because the aquatic environment is a key human resource," the UN says.
Water supplies are under pressure because of farming and deforestation. Indiscriminate tree clearing reduces water supplies by promoting water loss through run-off. Subsequent soil erosion reduces soil fertility and causes sedimentation in watercourses, further decreasing water-carrying capacity.
"An unhealthy environment means sick people, thus the essence of sustainable human health is sustainable management of the environment," Mr Toepfer said. What was most depressing, he added, was that solutions are well known.
Failure to act could have dire consequences. Whole societies have died out because they didn't manage water resources properly.
"On this World Water Day, which focuses on water for health, we should remember that the basis of human health is a healthy environment and that the basis for sustainable economic production is also a healthy environment," Mr Toepfer said.
