Water Quality Index elucidates the complexity in assessing water quality by converting the results of various parameters into a single number for a precise interpretation of the condition of concerning water. The present study focuses on implementing Multi-Criteria decision-making techniques, namely, Analytical Hierarchy Process and Analytical Networking Process, in estimating the relative weighted significance values of the water quality parameters based on three novel criteria like Cost, Potability, and Taste. The suggested Water Quality Index technique utilizes these weighted values of the water quality parameters in depicting and expressing the water quality level in the form of an index value. Dissolved Oxygen has emerged as the most persuasive factor in evaluating water quality for drinking purposes in this study. This paper has also suggested modifying the standard weighted arithmetic water quality index for higher accuracy in results. Furthermore, Sensitivity analysis is performed to corroborate the Multi-Criteria Decision Making approach in index assessment. The accuracy of the Water Quality Index analysis shall improve if a fixed set of criteria and their preference are asserted and justified based on which the water quality parameters are ranked. Their weighted significance values will be estimated accordingly.