Future global water shortages could be alleviated by huge freshwater reserves discovered beneath the ocean floor, according to a team of Australian and international scientists.

The scientists from Adelaide, the Netherlands, USA and the UK have found half a million cubic kilometres of fresh water in undersea aquifers located off Australia, China, North America and South Africa.

These aquifers are similar to the groundwater used in much of Australia and the rest of the world for drinking water and irrigation, and so could come in handy as existing supplies dwindle.

“The volume is a hundred times greater than the amount we’ve extracted from the Earth’s sub-surface in the past century since 1900,” says lead researcher Vincent Post, of Flinders University. “It could sustain some regions for decades.”

He says scientists previously considered these reserves rare, but the number and volume of the aquifers suggested that their formation was commonplace.

According to Vincent, they were probably filled by rainwater filtering into the water table during the last ice age, when these areas were above the lower sea level of the time.

The research team discovered the reserves by analysing previous seafloor water studies, some done for oil and gas exploration. The offshore drilling used to extract these fossil fuels could also reach these new water supplies, at a cost competitive with desalinating seawater.

However, there is a word of caution—these new reserves are non-renewable.

“We should use them carefully. Once gone, they won’t be replenished until the sea level drops again, which is not likely to happen for a very long time,” says Vincent.

Photo: Vincent Post

Credit: National Centre for Groundwater Research and Training

National Centre for Groundwater Research and Training, Flinders University, Vincent Post, Tel: +61 8 8201 5077, vincent.post@flinders.edu.au, www.groundwater.com.au