This study evaluated the suitability of groundwater from primary basins in the Tafilalet area of southeast Morocco for drinking purposes. Water samples were collected from 100 wells, and physicochemical parameters, including temperature, conductivity, pH, hardness, and organic and inorganic ion concentrations, were analyzed. The weighted arithmetic water quality index (WQI) was used as an ecological indicator for quality evaluation in relation to Moroccan drinking water criteria. Ten locations were chosen for monthly inspection based on their proximity to the potential sources of pollution. The study found a considerable improvement in water quality over a 15-year period (2004-2019), with three sites classified as "Good quality" and seven as "Poor Water". The analysis revealed that the pH values of all groundwater samples were within the acceptable range according to the World Health Organization (WHO) standards. The chloride ion concentrations decreased significantly over time, while the nitrate and sulfate concentrations increased. The hydrometric title of groundwater was very high in all study sites, with a significant proportion of alkaline earth metals present. The study suggests that the development of the sewerage network and supply and distribution of drinking water in the region has led to improved water quality. The study demonstrated changes in the physicochemical properties of groundwater in the Tafilalet region of Morocco over a 15-year period, with an overall improvement in water quality.