SUMMARY
To evaluate the groundwater of Pointe-Noire for human use, it was necessary to determinate the various parameters influencing the quality of water of the coastal sedimentary basin. Their physicochemical elements were followed during all the hydrological cycle of the year 2015 in 16 piezometers(drilling sand well). The results of the chemical analyses were treated by hydrochimic and statistical methods. Spatial of the elements shows the same evolutionary pace as that observed for chloride, sodium, sulphates, magnesium and calcium. This reveals that water of drilling sand the wells of Point-Black is characterized by low contents dissolved salts. This would be explained by the importance of the surface food. The Analysis in Principal Components and Ascending Hierarchical Classification indicate that the mineralisation of this wate ris controlled by three great phenomena: the mineralisation which results in the hydrolysis of minerals silicated for groundwaters, the pluvio lessivage of the grounds for surface water and, of the human activities in the production of pollutingwaste. This study also shows that water of Point-Blackis contaminated by total germs, fecal coliformes and totals which are the consequence of are centanthropic pollution.