Due to the current trends of rising numbers of the human population, as well as increasing living standards, wastewater treatment plants are exposed to changes in the quantity and quality of input wastewater. Such changes can affect the efficiency of the operational work of the wastewater treatment plant. There are many input and output parameters of the wastewater quality indicators (Biochemical Oxygen Demand through 5 days, Total Suspended Solids, Chemical Oxygen Demand, etc.), as well as input and output hydraulic parameters (flow of wastewater). There is a need to consider all of these and make decisions about the efficiency of the wastewater treatment plant. Among all the procedures and methods, a multicriteria decision is one that could be applied in this research. The Paper will present the application of the Multi Composite Programming and Promethee method for the real case study of the Parkandabad water treatment plant in Mashhad, Iran.