Extensive freshwater reservoirs have been discovered beneath the oceans

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Lisa Winter

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184 Extensive freshwater reservoirs have been discovered beneath the oceans

Scientists have discovered enormous reserves of fresh, low salinity water in pockets under the ocean. This has the potential to bring clean drinking water to those who are water insecure for decades to come. The findings were announced in the December 5 issue of Nature by lead author Vincent Post from the School of the Environment at Flinders University.

There is likely half a million cubic kilometers of freshwater (about 1.3 x 1017 gallons) stored in pockets on continental shelves below the ocean floor. While the existence of these freshwater reservoirs weren’t news to environmental scientists, the full extent was quite a surprise. 


These reservoirs formed hundreds of thousands of years ago, when the sea levels were much lower due to so much water being tied up into glaciers. Rain water collected in divots and was ultimately covered over by sediment and clay. When the salty ocean water levels became higher about 20,000 years ago, the pockets of freshwater were protected underneath.

This presents a huge opportunity to tap into the aquifer for a source of drinking water. Traditional methods of filtering sea water for human consumption is expensive and leaves hypersalinated water as a byproduct. Because the water found in these reservoirs does not have such a high salt content, it could be a much more desirable source of potable water.

There are, of course, some obstacles that will need to be addressed before the water can be used. The primary problem is going to be accessing the water so that it can be pumped to where it needs to go. One potential solution is drilling into it offshore and bringing it back in, and another solution would include drilling into the ground from land, and cutting across to reach the reservoir and pump it directly back to land. Whichever approach is used, a great amount of care must be taken so that the freshwater is not contaminated. 

Water insecurity is an issue that one in three people face around the globe, with freshwater becoming an increasingly desired commodity between pollution and growing populations. While there is potential to provide enough water to last for several years, it is a very finite resource. Once it is gone, there will not be more in any amount of time worth waiting for.