In Egypt, where the annual rainfall in the desert areas is less than 30mm a year, and around 80mm for other parts of the country, water is liquid gold. Yet in the Sahara Desert, rich deposits of underground water give rise to oases on the surface, which support small communities. The Nile Delta has suffered subsidence from groundwater pumping, but the hard limestone underneath the desert stops the same phenomenon happening to oases. Yet, the water may run out someday. Strict regulations have been put in place to stop over excavation of the underground reserves. In the latest in our series of features from Egypt, we go to the Bahariya Oasis, for a glimpse of life among Saharan sand dunes.