Geologists revealed a new groundwater map that shows that the water supply in the Earth's upper crust could submerge continents as deep as 590 feet (179 meters), however, not all of it can be retrieved for human use. The map detailing how underground water is distributed is the result of the collaboration between researchers from different universities such as the University of Victoria, University of Texas at Austin, the University of Gottingen and the University of Calgary, according to Gizmodo.

The researchers discovered an estimated 22.6 million cubic kilometers of groundwater. "This has never been known before," hydrogeologist Tom Gleeson said about their discovery, according to a press release. "We already know that water levels in lots of aquifers are dropping. We're using our groundwater resources too fast - faster than they're being renewed."

The findings are a great source of information for scientists in different fields such as hydrology, atmospheric science, geochemistry and oceanography for sustainable water management, Gleeson added, according to the Ecommerce Journal.

The study revealed that out of the 22.6 million cubic kilometers of groundwater, 6 percent is considered modern (less than 50 years old), according to Nature Geoscience. 

Areas that have huge underground water reserves are the Amazon Basin, the Congo, Indonesia, and the Rocky Mountains in North America.

"Intuitively, we expect drier areas to have less young groundwater and more humid areas to have more, but before this study, all we had was intuition," said Kevin Befus, one of the study authors, according to the DailyMail. "Now, we have a quantitative estimate that we compared to geochemical observations."