World faces 'water-energy' crisis: UN

Surging populations and economies in the developing world will cause a double crunch in demand for water and energy in the coming decades, the UN said today.

In a report published on the eve of World Water Day, it said the cravings for clean water and electricity were intertwined and could badly strain Earth's limited resources.

"Demand for freshwater and energy will continue to increase over the coming decades to meet the needs of growing populations and economies, changing lifestyles and evolving consumption patterns, greatly amplifying existing pressures on limited natural resources and on ecosystems," the report said.

Already, 768 million people do not have access to a safe, reliable source of water, 2.5 billion do not have decent sanitation and more than 1.3 billion do not have mains electricity.

About 20% of the world's aquifers today are depleted, according to the report.

Agriculture accounts for more than two-thirds of water use.

The World Water Development Report, the fifth in the series by the UN Educational, Scientific and Cultural Organisation (UNESCO), is an overview collated from data from scientific studies and investigations by agencies.

It said ever more freshwater will be needed for farming, construction, drinking, cooking, washing and sewerage, but also for energy production, 90% of which uses water-intensive techniques today.

The report gave this snapshot of the future:

Global water demand is likely to increase by 55% by 2050.

By then, more than 40% of the world's population will be living in areas of "severe" water stress, many of them in the broad swathe of land from North Africa and the Middle East to western South Asia.

Asia will be the biggest hotspot for bust-ups over water extraction, where water sources straddle national borders.

"Areas of conflict include the Aral Sea and the Ganges-Brahmaputra River, Indus River and Mekong River basins," said the report.

Global energy demand is expected to grow by more than a third by 2035, with China, India and Middle Eastern countries accounting for 60% of the increase.

In 2010, energy production gobbled up 66 billion cubic metres (2,300 billion cubic feet) of fresh water more than the average annual flow of the River Nile in Egypt.

By 2035, this consumption could rise by 85%, driven by power plant cooling systems that work with water.