Scientists in New York have found a massive deposit of fairly fresh water deep below the ocean floor, raising the possibility of underwater drilling as a solution to a growing global water crisis.

The research team out of Columbia University said the aquifer spans at least 350 kilometres from Massachusetts to New Jersey and holds an estimated 2.79 trillion litres worth of water, making it the largest such discovery in the world.

If the water was on land, it would create a lake measuring an estimated 38,850 square kilometres. For context, Lake Erie is 25,744 square kilometres.

Scientists have known about freshwater deposits under the seafloor since the 1970s when oil drilling sometimes brought up freshwater, but the theory until now was that these were small pockets scattered around the bottom of the ocean, instead of vast aquifers spanning multiple states.

“We knew there was fresh water down there in isolated places, but we did not know the extent or geometry,” Chloe Gustafson, a PhD candidate at Columbia and the lead author in the study, said in a news release.

To make the discovery, the researchers used dropped receivers onto the seafloor to measure electromagnetic waves. Because salt water is a better conductor than fresh water, the team was able to use the electromagnetic waves to distinguish areas of freshwater.

The researchers suggest the freshwater made it under the seabed in two possible ways: either by being drawn to the ocean floor by tides, or by being trapped in scattered pockets under the U.S. continental shelf as glaciers melted approximately 15,000 years ago.

The research, which was published this week in Scientific Reports, suggests this is not the only such deposit and they could be found along shorelines around the world.

“It could turn out to be an important resource in other parts of the world,” said Gustafson.

According to the World Wildlife Federation, two-thirds of the world’s population may face a water shortage by 2025. 

While parts of the aquifer aren’t completely drinkable -- the saltiest parts contain less than half the salt of seawater -- extracting the water and desalinating it could prove as a cost-effective strategy to provide freshwater to parts of the world that are running out, such as California, South Africa and the Middle East. 

“We probably don’t need to do that in this region, but if we can show there are large aquifers in other regions, that might potentially represent a resource,” said Columbia University geophysicist Kerry Key, a co-author on the study.