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.
Freshwater rivers and lakes are subject to seasonal floods and droughts that can limit their availability for people and for agriculture. At present only 5% of arable land is irrigated.
What is ground water?
When water falls as rain or snow, much of it either flows into rivers or is used to provide moisture to plants and crops. What is left over trickles down to the layers of rock that sit beneath the soil.
And just like a giant sponge, this ground water is held in the spaces between the rocks and in the tiny inter-connected spaces between individual grains in a rock like sandstone.
These bodies of wet rock are referred to as aquifers. Ground water does not sit still in the aquifer but is pushed and pulled by gravity and the weight of water above it.
The movement of the water through the aquifer removes many impurities and it is often cleaner than water on the surface.
Now scientists have for the first time been able to carry out a continent-wide analysis of the water that is hidden under the surface in aquifers. Researchers from the British Geological Survey and University College London (UCL) have mapped in detail the amount and potential yield of this groundwater resource across the continent.
BBC has the full article
