A crisis is looming over water shortages worldwide. By 2025 more than half the nations in the world will face freshwater stress or shortages and by 2050 as much as 75 percent of the world's population could face freshwater scarcity. So say Mike Hightower and Suzanne Pierce, water experts at Sandia National Laboratories, in an article they wrote that appeared in a recent issue of Nature.

"This growing international water crisis is forcing governments to rethink how they value and use and manage water, especially because economic development hinges on water availability," they say.

"Drinking water supplies, agriculture, energy production and generation, mining and industry all require large quantities of water. In the future, these sectors will be competing for increasingly limited freshwater resources, making water supply availability a major economic driver in the 21st century."

Freshwater withdrawals already exceed precipitation in many parts of the U.S., with the worst shortfalls often in areas with the fastest population, particularly in the southwest. But, this is also very much a global problem.

What can be done to help solve the water dilemma? The answer is not simple and will involve usage of all water sources - more than just freshwater supplies as has been the primary focus in the past. Innovative treatments will have to be used - treatments using advanced membrane separation technologies, as well as treatment of nontraditional water sources such as wastewater, brackish groundwater, seawater and extracted mine water.

Hightower and Pierce say that to some extent this is already happening. In the United States, wastewater reuse is growing by 15 percent per year.

"There are other, cheaper ways to increase water productivity, such as improving water conservation and efficiency," Hightower and Pierce said in the article. "But water reuse can help to expand these traditional approaches by matching the quality of water supplies to needs, and substituting nontraditional water for freshwater where appropriate."

As an example, waste water, sea water or brackish groundwater could be used by electric power plants for cooling and processing instead of freshwater; switching to renewable energy technologies that do not need water for cooling, such as wind and solar electric; and introducing technologies to condense evaporation from cooling towers and capture and reuse the water.