Previous assessments of urban water supplies typically used what is known as a "runoff-based approach" that takes into account factors such as river flows and rainfall amounts, researchers said, but other factors should also be taken into consideration.
Those previous assessments did not consider the infrastructure used to maintain urban water supplies, such as water stored in aquifers, lakes, reservoirs or water that's pumped in to an area and stored, they said.
Jim Jawitz, a University of Florida soil and water science professor, and Julie Padowski, who earned her doctoral degree from UF and is now a postdoctoral researcher at Stanford University, said using the runoff-based approach suggests 47 percent of the total U.S. population is vulnerable to water scarcity issues.
However, they said, when infrastructure was accounted for the number dropped to just 17 percent of the population.
But despite the good news about water, Padowski said, conservation should be a front-and-center topic for many years to come.
"As population growth increases, we don't have more resources to tap -- we can't just find another lake or another river to dam," she said. "It's going to come down to sharing, conservation and efficiency."