Disposal of untreated sewage into surface waters is common in most developing countries. Any physico-chemical, or biological condition that prevents the designated uses of a water body represents poor water quality. This study was carried out on Middle Manyame River, a major source of potable water in Chinhoyi town. The study sought to ascertain the impacts of discharging untreated sewage on the water quality of Middle Manyame River. The following parameters were determined using APHA standard methods; nitrates, phosphates, pH, temperature, dissolved oxygen (DO), total dissolved solids (TDS), and biological oxygen demand (BOD). Sampling was done in November 2013, March 2014, and May 2014. All the parameters, except for pH and temperature, exceeded acceptable water quality standards for the sites downstream of the sewage discharge points. This indicated that the improper sewage discharge was the major contributor to poor water quality, among other activities such as agricultural runoff. It was concluded from the study that sewage effluent from the Municipality of Chinhoyi sewage works was mainly responsible for pollution along Middle Manyame River. This pollution has also put the river at risk of eutrophication. It was recommended that there should be rehabilitation and upgrading of sewage systems in Chinhoyi.