The hydric stress defines itself as an insufficiency of water of satisfactory quality, to be able to answer the human and environmental needs. Although numerous populations already live in regions knowing a hydric stress, it is planned that before 2025, the part of world population living in such zones will increase by 35 %, that is 2.8 billion people. In fact, we can already plan in a near future, the appearance of conflicts for the water which will take the same importance as the conflicts around the oil.
70 % of the water consumption in the world is attributable in the agriculture (farming) and the portion of the water consumed in cities represents less than a quarter, even less in Africa. In Asia and in the Pacific, the agriculture (farming) represents approximately 85 % of the water consumption.
Nevertheless, it is demonstrated that the lack of water resources does not establish (constitute) a major cause of the insufficiency of the systems of the water supply and of purification of most of the low-income cities. The problem is more connected to the mismanagement of these resources.