This work concerns the reuse of treated wastewater from Er-Rachidia wastewater treatment plant (WWTP) in the mixing of ordinary C20/25 concrete, to reduce the overexploitation of non-potable groundwater, avoid its discharge into watercourses and reduce the risk of environmental pollution due to its mineral and organic matter load. In this respect, three types of mixing water were used in this study: drinking water (DW), non-potable groundwater (GW), and treated wastewater (TW). The results recorded for each type of mixing water, in the fresh and hardened state of concretes, were compared with the requirements of the standards. The obtained results show that the treated wastewater does not have any adverse effect upon the quality of the concrete; it has shown an improvement of the mechanical strength from the first stage, a similar density, setting time, and porosity and a slight decrease of the workability compared with the control concrete. A one-way analysis of variance (ANOVA) of the mechanical performance of concrete at different cure times (7, 14, 28, and 90 days) has shown that there is no significant decrease in the mechanical performance of concretes based on TW and GW compared with concretes formulated with DW. Through this study, the substitution of drinking water by treated TW and GW will help to minimize the footprint of construction materials on natural resources. From a point of view of the mechanical performance, TW and GW improve the mechanical performance of concrete. Additionally, it makes wastewater treatment plants more economically attractive and contributes to sustainable development