The annual amount of rain is 100 billion m³, of which 80 % evaporate in the atmosphere.

The water resources are estimated at 19,1 billion m³/year, of which 12,4 billion originate from surface water and 6,7 billion from ground water.

From 12,4 billion of the surface water, only 6 could be mobilised by dams. Currently only 4 billions are mobilised by nearly 110 dams. The average annual regularised volume has been 2,7 billion m³ between 1995 and 1998 .

From the 6,7 billion of groundwater resources, 5,1 billion are located in Sahara. The remaining 1,6 billion m³ is already mobilised at a rate of 80 %, mainly by wells and borings.

So it could have been on the maximum an annual volume of 7.6 billion m3, which according to the last studies could cover the water needs for urban, agricultural and industrial uses until 2015. After that, it will be necessary to re-use waste water for irrigation, to pump the non renewable waters in the northern Sahara, and to desalinate sea water in order to satisfy the demand.