New research suggests there’s a large untapped resource for many of the increasingly water-limited regions of the U.S. and around the world: brackish groundwater, which, in theory at least, would require much less energy to desalinate than seawater.

The amount of brackish groundwater in the United States is about 800 times greater than the total amount of groundwater withdrawn nationwide for all uses, according to a U.S. Geological Survey study. So, using even a fraction of that resource could dramatically improve the prospects for water-starved communities, especially as potable water becomes more scarce, as climate change models predict.

While about a fifth of the nation’s water supply comes from fresh groundwater, less than 1 percent currently comes from brackish groundwater.