The Water Quality Index (WQI) is a method used to assess the overall water quality from data of analyze for understood by managers and decision-makers. In this study, the WQI with twelve physicochemical parameters were used to evaluate the overall sixty eleven wells of the groundwater of Mnasra in the northeastern of Morocco, is about 488 km². The results of WQI showed a difference from 35.45 to 660.22. According of standards the WQI values, it is observed that only one location study is found unsuitable for drinking (WQI > 300).  Where, the results show that the highest values effective weight value belong to the NO3^-, Cl^-, Na⁺ and K⁺ parameters compared with the other parameters. Consequently, environmental pollutants negatively affect the Mnasra groundwater. Therefore, necessary protection measures should be taken as related to planned usage of the groundwater.

Keywords: Water samples, Correlation, WQI,  Mnasra region, Morocco.