With around a quarter of the world’s population lacking access to safe drinking water, the discovery of the hidden aquifer, one of many deposits known to exist across the globe, has highlighted the existence of potentially drinkable water sitting below the seabed.

“Offshore groundwater could serve as a backup source for coastal communities under stress from drought or population growth,” Kerry Key, president and geophysicist at Deep Blue Geophysics, a company that applies electromagnetic geophysics to environmental and resource exploration, told Newsweek.

“Globally, these hidden reserves could be a lifeline in regions facing severe water scarcity, though responsible management will be critical to avoid overuse,” he added.

Why It Matters

The discovery of a new source of fresh water off the East Coast comes as America’s drinking water has been increasingly scrutinized—more studies have been highlighting harmful contaminants in supplies across the country.

These contaminants have a wide range of impacts on human health, with pollutants like arsenic affecting birth outcomes, even at low exposure levels, while communities exposed to PFAS chemicals in drinking water have been found to have a 33 percent higher incidence of certain cancers.

“As a potential and alternative source of freshened water, it could provide some relief in areas where drinking water contamination is a problem,” Brandon Dugan, a professor of geophysics at Colorado School of Mines and co-chief scientist with Expedition 501, told Newsweek.

Why Fresh Water Can Be Found Under Seabeds

The Expedition 501 offshore team set sail to investigate the potential origins of the fresh water believed to be within the Atlantic continental shelf off New England in April.

“As a scientific community we have had observations and inferences that fresh water was present in sediments below the ocean floor since the 1960s,” David Boutt, a professor in the Department of Earth, Geographic, and Climate Sciences at the University of Massachusetts-Amherst, told Newsweek.

There are multiple reasons why fresh water can become “trapped” in ocean floor sediments, such as when sea level was lower, “these areas were exposed to rainfall and liquid fresh water could infiltrate into the sediments and subsequently be trapped by rising seas and additional sediment,” Boutt said.

Another scenario is that “when glaciers covered this area, the fresh meltwater infiltrated the coastal sediments and became emplaced under the ocean,” he added.

Also, fresh water can exist beneath the seabed because “the aquifers, the geologic formations that hold water and that we tap for water supply on land, don’t just stop at the shoreline, they extend offshore,” Holly Michael, director of the Delaware Environmental Institute at the University of Delaware and a non-offshore member of the Expedition 501 scientific team, told Newsweek.

“Our preliminary and initial results indicate glacial water as the most likely candidate,” Dugan said. “Our ongoing research will help decipher the components, as well as how the freshened water is interacting with the seawater above.”

Could This Water Be Drinkable?

Because the fresh water has likely been under the ocean floor for a very long time, “I suspect that the water is not suitable for drinking as it is,” Michael said, as “it has had time for the rocks to actually dissolve into it, so it likely has high concentrations of solutes that might not be suitable for drinking.

However, she added that there are ways of treating the water to make it drinkable and that as “we deplete our water resources on land, particularly in very densely populated coastal areas, we are going to need to consider alternate sources of water.”

The water would likely have to “undergo some small level of desalinization,” Boutt said, as the water would probably have a level of salts “above the tolerance of drinkable water.”

Dugan said that samples of water they found and have been studying are “significantly less salty than seawater, some even as low as one part per thousand salinity.”

“The water could be suitable for drinking if it were to be treated following the same processes as standard drinking water sources,” he said.

While the water will need to be treated before drinking, “it’s likely much cleaner than many modern groundwater or surface water sources exposed to pollution,” Key said.

The water likely originates from a “pre-pollution” era, meaning it could be less polluted than current sources of drinking water like groundwater and surface water, Henry Bokuniewicz, a professor in the School of Marine and Atmospheric Sciences at Stony Brook University, New York, told Newsweek.

This indicates it most likely will not be contaminated with “chemicals made by humans,” Boutt said, pointing to PFAS chemicals, which are classified as a Group 1 carcinogen by the International Agency for Research on Cancer.

Groundwater has recently been found to be widely contaminated with these carcinogenic chemicals, which are found in consumer and industrial products.

“Groundwater and surface water contamination has always been an issue, particularly, animal and human waste and their associated microorganisms were probably always a concern,” René Price, a professor in the Department of Earth and Environment at Florida International University, told Newsweek.

She added that pesticides, herbicides, gasoline and numerous other chemical compounds have “contaminated drinking water since the industrial revolution.”

“If the freshwater in this undersea aquifer is hundreds or thousands of years old, it would be expected to be free of those industrial age contaminants,” she said.

Meanwhile, PFAS, microplastics and pharmaceuticals are “more modern-day concerns,” Price added.

What This Means for America’s Drinking Water Supply

The findings show that “we do have alternative sources of freshened water along the U.S. coastlines,” Dugan said.

Although, he added that “if, when, how, and where that water could be used by society will require more studies on appropriate pumping rates and volumes for use, who would govern and manage the water, and where the water would be treated and distributed.”

“Such advancements would have to be done in coordinate with local communities, states, and the federal government as the water extends from state to federal waters,” he said.

The finding may therefore have tremendous potential, but getting the water out of the ground, without harming the surrounding nature, as well as deciding who owns it and can have access to it are significant hurdles that stand in the way of the water reaching public water systems.

“I don’t see these resources being a solution to our drinking water issues—at least in the next decades,” Boutt said.

He said that, in the specific case of the aquifer found off the East Coast, “there are more economical solutions to our water challenges that would inhibit the cost of tapping into this resource and associated treatment needs.”

“It does expand the overall portfolio of fresh to brackish water availability, though, which under certain specific cases might be options for communities with a dire need of low-cost treatable water,” he added.

Bokuniewicz also said that this finding does not do much for America’s drinking water supply, “except maybe in extremely stressed local areas, but in general, it’s just too much trouble to find and get out.”

He added that, while in principle, this water could resolve some issues with drinking water contamination in the U.S., it is “probably too much effort and uncertainty.”

“The best solution for drinking water supplies is still to protect our clean, freshwater resources now,” Michael said. “The more we can do that, the better off future generations will be.”

“Offshore groundwater could provide coastal communities with a cleaner alternative, but it won’t fix widespread contamination in rivers and aquifers,” Key said. “Addressing pollution at its source remains essential.”

What Happens Next

The Expedition 501 team are now analyzing nearly 50,000 liters of the water back in their labs around the world to try to figure out where the water came from.

This article contains reporting from The Associated Press.

Full Interview Below

Newsweek‘s interview with Brandon Dugan, co-chief scientist of Expedition 501.

Q1: Why is it possible to find fresh water under the seabed?

“There are three different pathways for fresh water to exist in the sediments beneath the sea. One is that rainfall onshore on high topography (for example mountains) seeps into the ground and travels downward and toward the sea.

“A second is during the geological past when seas were hundreds of feet lower than today, more of the continental shelf was exposed to rainfall that seeped into the ground. Then sea level rose and trapped that rainwater in the sediments.

“A third is that during large glaciations, some glaciers extended out onto the continental shelf and water from the bottom of those glaciers was pushed into the ground from the force of the glaciers. The glaciers then melted, and sea level rose and trapped the rainwater in the sediments.

“Our preliminary and initial results indicate glacial water as the most likely candidate; there could however be a small component of modern fresh water being charged in local geologically high locations. Our ongoing research will help decipher the components as well as how the freshened water is interacting with the seawater above.”

Q2: Could that water be suitable for drinking water? Could that water be cleaner than groundwater or surface water, which are used for drinking water?

“The freshened water we found and are studying is significantly less salty than seawater, some even as low as one part per thousand salinity. The water could be suitable for drinking if it were to be treated following the same processes as standard drinking water sources.

“Some of the freshened water would also require desalination as well, but less intensive than seawater due to its lower salinity. If the water is from an older source, such as a glacier, it could be cleaner in terms of PFAS because it would have been emplaced in the aquifer before PFAS existed.”

Q3: What does this mean for drinking water supplies in the US?

“The documentation and ongoing characterization of this offshore freshened groundwater system shows that we do have alternative sources of freshened water along the U.S. coastlines.

“We are currently focusing on addressing how much is there and how it was emplaced. If, when, how, and where that water could be used by society will require more studies on appropriate pumping rates and volumes for use, who would govern and manage the water, and where the water would be treated and distributed.

“Such advancements would have to be done in coordinate with local communities, states, and the federal government as the water extends from state to federal waters.”

Q4: Do you think this could resolve some issues with drinking water contamination in the US?

“As a potential and alternative source of freshened water, it could provide some relief in areas where drinking water contamination is a problem. We still need to do a lot of work to address where waters could be produced and under what conditions they should be produced, all of which would be done in coordination with the communities who could be served by these waters.

“Another aspect that we need to consider—and we are—is the age of this water and how quickly it is recharged with fresh water or being salinated by seawater. This will influence how much water could be used and whether it is a finite use or a renewable use.”