Scientists say the notoriously dry continent of Africa is sitting on a vast reservoir of groundwater.
They argue that the total volume of water in aquifers underground is 100 times the amount found on the surface.
The team have produced the most detailed map yet of the scale and potential of this hidden resource.
Writing in the journal Environmental Research Letters, they stress that large scale drilling might not be the best way of increasing water supplies.
Across Africa more than 300 million people are said not to have access to safe drinking water.
Demand for water is set to grow markedly in coming decades due to population growth and the need for irrigation to grow crops. Read More