The Nubian Sandstone Aquifer System (NSAS) is the world´s largest ‚fossil‘ water aquifer system meaning that the water is ancient and non-renewable, much like the mineral resources on which countries rely for their prosperity. Lying beneath the four African countries of Chad, Egypt, Libyan Arab Jamahiriya (Libya), and Sudan, it covers some two million square kilometers. Groundwater has been identified as the biggest future source of water to meet growing demands and development goals in each country.