This paper relates to an experimental investigation about the treatment processes of large quantities of used water from agricultural uses. It is collected after its natural mixing with domestic and industrial used waters, treated according to administrative laws, and drained by gravity into an open channel and spilt into a lake where it lies waiting its natural evaporation. This transfer in state could be accepted as a natural cycle, but water is the scarcest element in this and area. Water is pumped from drilled wells; there is very little rainfall and no rivers. Recycling of the used water would be an optimal solution. The goal of this investigation is to treat this water completely at the channel downstream and recycle it. Some experiments have been conducted using biological, mechanical, chemical and thermophysical processes to obtain acceptable water that could be reused according to required properties in the water for agricultural needs. Obviously, it could also be supplied to industrial or domestic demands. This could be an ecological solution in preserving an important region from disaster due to aridity and the resulting consequences to future generations.