Drinking water treatment aims to eliminate physical, chemical, and biological impurities to mitigate health risks, ensure adequate water quality, and promote sustainability. However, the treatment process often requires significant energy, chemicals, and technological inputs, which can lead to increased secondary environmental impacts and higher water production costs. This study aims to evaluate the sustainability of three wastewater treatment facilities (WWTPs) based on their Water Quality Index (WQI). The facilities under investigation are Al-Barakiya Treatment Plant, Al-Maymira Treatment Plant, and Al-Rustamiyah Treatment Plant, all located within the research area. Using the "Canadian Council of Ministers of the Environment" (CCME) framework, the WQI was employed to assess both raw and treated water quality based on fundamental water characterization criteria. The study involved the regular collection and testing of water samples from January 2023 to December 2023. The raw wastewater quality indices for the three plants were as follows: Al-Rustamiya Treatment Plant (81.232), Al-Maymira Treatment Plant (79.307), and Al-Barakiya Treatment Plant (80.931). The treated water from these facilities received a "good" quality rating, with WQI values ranging from 94.620 to 94.718. This study demonstrates that while the CCME approach is effective in evaluating the quality of treated wastewater, the variations in WQI results reflect the balance between achieving high water quality and addressing the sustainability challenges inherent in the treatment process.