The Karbala-Al-Muwahid Water Treatment Plant (Aoun Road) is the main plant feeding Karbala Governorate by drinking water. It distributes water through three lines: Aoun, Al-Husseiniyah, and Al-Markaz. Therefore, studying this plant is necessary to improve the quantity and quality of water and avoid problems that occur in the present and future resulting from the increase in the population in recent years due to immigration, as well as the large number of million visits there, as it is a religious province that visitors come from everywhere, which leads to increasing demand for water. In this study, the performance efficiency of the Karbala-Al-Muwahid water treatment plant was evaluated, and the plant’s operational problems. This study covered the period from 1/1/2023 to 1/11/2023. The monthly laboratory tests of quality parameters (turbidity, alkalinity, hardness, T.D.S, Mg+2, Cl-1, Na+1, K+1, E.C, and pH) for influent and effluent water, the water discharges leaving the plant for each month, and the corresponding temperatures were collected for the above period. The finding showed that the plant has a high removal efficiency of 95%, and the water quality was within the Iraqi standard specifications.