From the Los Angeles Times  “Our maps and estimates show where the groundwater is quickly being renewed and where it is old and stagnant and non-renewable,” said Tom Gleeson, a hydrogeologist at the University of Victoria and leader of the study, in the article.

According to the research team, the upper 1.2 miles of the Earth’s crust currently holds six quintillion gallons of groundwater, shared the article. Above ground, the amount would form a layer of water 600 feet high across the globe.

…The measurements showed that 5.6 percent of groundwater is less than 50 years old, a finding Gleeson noted was the biggest surprise of the study.

“This global view of groundwater will, hopefully, raise awareness that our youngest groundwater resources — those that are most sensitive to anthropogenic and natural environmental change — are finite,” she concludes.