In this research, the water quality and the functioning mechanism of the human sewage treatment plant are evaluated at the entry, stages and outlet. In this regard, the microbial, chemical and physicochemical properties of wastewater samples are evaluated at the mentioned points. Afterwards, the relationship in between the microbial and chemical pollutants are investigated. Finally, corrective solutions are presented to improve the performance of the treatment plant by having the detailed information on the microbial, chemical and physicochemical conditions of wastewater at all the points of treatment plant. In this regard, microbial monitoring is performed using the general TBC microbial kit and specific microbial kits including APB, FP, IRB, NRB, Aero, SRB and TRB. The TBC kit is applied to measure the total number of bacteria in wastewater samples and other kits are interrogated to determine each type of bacteria. In the following step, the physicochemical and chemical parameters are monitored using reference techniques. The TBC level is 105 cfu/ml at the entry point of the human sewage and its level reaches to 103 cfu/ml at the second and third stages. Finally, the TBC value reaches to 102 cfu/ml in the outlet. The process of reducing TBC from the inlet to the outlet prove the ideal performance of human sewage treatment plant. The performance trend of the treatment plant is suitable for reducing other types of bacteria. In the most cases, the bacteria level is reached from high to moderate level and in some cases to low level.