The proposed study assesses the quality of water to find out the principal contributing factor responsible for the pollution in River Brahmani, India. These factors help the management and policymakers to set a marginal water quality standard. Physical, chemical, and biological parameters are taken for the study. Due to the notable dissimilarity in water quality parameters and spatiotemporal variability, significant objectives are proposed to assess the river water quality. The work presents a functional index which can be implemented for the comparative assessment of water quality across the River Basin controlled by several factors. The results showed that the quality of water could be improved by removal of total chromium for all the three seasons. The parameters such as sodium, potassium, lead, and nickel have positive effect and are considered to have high interference rate than that of other parameters such as chloride, cadmium, boron, sulfate, phosphate, fluoride, copper, zinc, nitrate, nitrite, and ammonia, which have negative effects on functional water quality index and are accounted as the parameters having low compliance rate. The water quality indexing methods done by previous authors are discussed extensively in the paper, which can provide an overall idea about indexing for further research.