A comparative assessment of the novel water pollution index and the water quality index using empirical data: Improving water quality evaluation

Abstract Different water assessment indices have been employed in the evaluation of water quality for human use. However, these methods have their peculiar drawbacks. This study applied the novel water pollution index (WPI) against the water quality index using empirical data (packaged and groundwater sources) from some parts of Ghana. The study showed that the WPI method is flexible and easy to compute compared to WQI. In this study area, WPI ranged from 0.22–0.31 and 0.23–0.32 for packaged water obtained from production and vending sites respectively. However, the WQI outputs were 0.12–0.36 (production site) and 0.27–0.42 (vending sites). Though the water samples from both sources were excellent for drinking, the wide variation in the WQI suggests the biases resulting from the selection of the weighting factors for the various parameters. Considering the groundwater sources applied in this study, 74% as against 93% and 19% as against 5% of the samples were excellent and good water sources based on the WPI and WQI respectively. These disparities are largely attributed to the biases posed by the quality rating and weighting factors which are researcher-described.