Increasing demands for fresh water and energy will strain resources in nearly all regions, especially in developing and emerging countries undergoing rapid economic growth, a UN report says.
Richard Connor, lead author of the report, told a news conference yesterday that water and energy supplies are interdependent because water is required to produce nearly all types of energy.
He warned that growing competition for the resources could lead to legal disputes and social upheavals.
According to the World Water Development Report 2014, the challenge is to provide energy and clean water to all people.
Today, an estimated 768 million people don't have access to clean water, although by some estimates the number could be as high as 3.5 billion, and 2.5 billion don't have access to toilets or latrines, the report said.
At the same time, more than 1.3 billion people still lack electricity and roughly 2.6 billion use solid fuels, mainly wood and other kinds of biomass, for cooking.
"The fact that these figures are often representative of the same people is evidenced by a close association between respiratory diseases caused by indoor air pollution, and diarrhea and related waterborne diseases caused by a lack of safe drinking water and sanitation," it said.
The report said global demand for water is projected to increase by some 55 per cent by 2050, mainly because of growing demand from manufacturing, thermal electricity generation, and domestic use.
Global energy demand is also expected to grow by more than one-third by 2035, with China, India and Middle Eastern countries accounting for about 60 per cent of the increase. Electricity demand is expected to grow by approximately 70 per cent during the same period, the report said.
"This enormous increase in the demand for energy and electricity in particular will place tremendous pressure on already limited water resources," Connor said, pointing to the diminishing supply of the world's groundwater and the 20 per cent currently being overexploited.
He said "the challenge will be greatest in developing and emerging economies where we see the greatest demand for energy, and where other water-dependent sectors such as agriculture, industry and urban areas are often growing at an unprecedented pace".
According to the report, approximately 90 per cent of global power generation is "water intensive.