The present study discussed the maintenance systems applied in the wastewater treatment plants (WWTPs). The Madaba municipal wastewater treatment plant was chosen as a case study. In fact, the municipal wastewater treatment plants should be continuously under maintenance. This is because these types of the infrastructure are costly to run. Therefore, the excellent maintenance steps should be intensively implemented. The study aims to evaluate the maintenance system adopted by the Madaba WWTP and to suggest a suitable methodology to improve the present condition of the studied WWTP. The data collection stage majorly focuses majorly on the specification of WWTP, stages of the treatment and the number of units, the current plan of the maintenance, and the cost spent on the maintenance of WWTP facilities. These data were obtained through documented reports, field visits and visual observations, interview with the engineers and laborers. The results showed that the Madaba WWTP suffers from poor maintenance system for its operation management. Generally, this plant only adopts the routine visual observations for the treatment units and equipment. In addition, the documentation of the maintenance process are not employed. Far from these points, both planned and preventivemaintenance is not conducted. There is no budget set for maintenance of the facilities. It was found that the organizational structure of the Madaba WWTP did not include essential divisions and important units such as accounting and maintenance units inside the plant, where corresponding operations are carried out by the central headquarter of the parent company. Therefore, some maintenance operations have been delayed. Thus, the study recommends: to adopt the routine visual examination, detailed checking, and to approve the samples submitted by this study regarding these two examinations. In addition, all the assets in WWTP should be coded and make inventory of them in order to help control the process of planning, implementation, documentation and control of maintenance work and management. In addition, the study suggests restricting of the WWTP framework as suggested by this study Keywords: Maintenance; Management; Cost; Wastewater treatment; Replacement.