An index based quality evaluation of groundwater-a case study of Whitefield area in Bangalore, India

Conventional indices to describe the quality of water have been found to have several drawbacks. Hence, an attempt has been made to overcome these deficiencies by developing an improved system by incorporating a few modifications in the drinking water quality indices developed hitherto. Fifteen groundwater quality parameters were chosen for the study and categorised into four groups based on potability and hazard factor. These parameters were analysed for water samples drawn from 30 groundwater sources in the study area. A proposed drinking water quality index (PDWQI) was arrived at, and this was compared with the arithmetic and geometric indices as evaluated in this study, to depict its utility and adaptability. The results revealed that the geometric DWQI was higher than the arithmetic as well as proposed DWQI, while the geometric DWQI was lower than the proposed DWQI. All the indices had a high positive correlation (r = +0.99). The PDWQI clearly illustrated the degree of potability of groundwater for drinking purposes in regard of health threats, by indicating the degree of pollution caused by the various quality parameters. The comparison between the three indices clearly depicted that the PDWQI was the most reliable water quality indexing system, which enabled the reduction of issues of eclipsing as well as sensitivity, that is found to exist in conventional indexing systems.