Key Facts

Groundwater1
About 96% of all liquid freshwater on Earth is groundwater
Groundwater2
Recent surveys1 on groundwater in Africa concluded that there is 100 times more water under the continent’s surface than on it
Groundwater3
In India, a new tube well is sunk every six seconds on average

Photos: David Brazier, Akissa Bahri, Tom Van Cakenberghe
Sources:
Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.

Groundwater and Human Development: Challenges and Opportunities in Livelihoods and Environment
Tushaar Shah, International Water Management Institute http://publications.iwmi.org/pdf/H035884.pdf

Environmental Research Letters Volume 7 Number 2,
A M MacDonald et al 2012  Quantitative maps of groundwater resources in Africa
A M MacDonald, H C Bonsor, B É Ó Dochartaigh and R G Taylor
http://iopscience.iop.org/1748-9326/7/2/024009

1 Surveys carried out by British Geological Survey and University College London