Infrastructure / On the water frontDesalination can boost U.S. water supplies

Published 25 April 2008

More than 97 percent of the Earth’s water — seawater and brackish groundwater — is too salty to use for drinking water or agriculture; new report says that desalination would be a good way to meet water shortages in the United States, but that the environmental impact of large-scale desalination campaign should be carefully studied

Recent advances in technology have made removing salt from seawater and groundwater a realistic option for increasing water supplies in some parts of the United States, and desalination will likely have a niche in meeting the U.S. future water needs, says a new report from the National Research Council. A coordinated research effort with steady funding is required, however, to understand better and minimize desalination’s environmental impacts — and find ways to further lower its costs and energy use. “Uncertainties about desalination’s environmental impacts are currently a significant barrier to its wider use, and research on these effects — and ways to lessen them — should be the top priority,” said Amy Zander, chair of the committee that wrote the report and professor at Clarkson University in Potsdam, New York. “Finding ways to lower costs should also be an objective. A coordinated research effort dedicated to these goals could make desalination a more practical option for some communities facing water shortages.”

More than 97 percent of the Earth’s water — seawater and brackish groundwater — is too salty to use for drinking water or agriculture. Interest in desalination has grown in the United States as some regions face water shortages and contention over existing freshwater supplies. Though desalination still generates less than 0.4 percent of the water used in the United States, the nation’s capacity to desalinate water grew by around 40 percent between 2000 and 2005, and plants now exist in every state. Most use a method called reverse osmosis, which pushes water through a membrane to separate out most of the salts. The report recommends that federal R&D on desalination be planned and coordinated by the White House Office of Science and Technology Policy and funded at the level of existing desalination R&D programs — approximately $25 million a year. Currently there is no overall strategic direction to federal research on desalination, which is conducted by many agencies with varying goals. It also depends heavily on earmarks, which are unsteady sources of funding; from 2006 to 2007 federal funds declined by nearly 60 percent. Meanwhile, the private sector appears to fund the majority of the nation’s desalination research. Both the public and private sectors can contribute to the proposed research agenda, the report says.

Substantial uncertainties remain about the environmental impacts of desalination, the report says. Limited studies suggest that desalination may be less environmentally harmful than many other ways