For human needs and the balance of aquatic ecosystems, the quality of the water must be good. Man, through his activities, contributes to the degradation of water, and this disturbs human activities, the balance between the natural environment and the animal and plant species that live in this environment. Apart from its geographical situation, Chad enjoys a relative abundance of rivers and watercourses, which provide many advantages. These rivers and streams, which supply water to agricultural, industrial and commercial farms, also ensure the maintenance of the water table and the perenniality of heterogeneous wildlife environments. Despite the fact that these rivers and streams are subject to climatic hazards, Chad remains among the countries in the world where rivers and streams are very fishy but it appears that the results obtained in the state of physicochemical quality of the Chari waters highlight the impact of pollution generated by discharges from domestic, agricultural and industrial waters.