Assessment of groundwater quality in Patna district, Bihar, India, using the Water Quality Index method (Canadian Council of Ministers of the Environment method)

 In this study, we assessed the groundwater quality in Patna district, Bihar, India, using the Water Quality Index (WQI) method, specifically the Canadian Council of Ministers of the Environment approach. Secondary data from various agencies (2004 – 2020) were analyzed to evaluate physicochemical parameters and spatial-temporal trends. Results indicated that while most samples fell within the permissible limits, samples from some locations showed elevated pH, electrical conductivity, hardness, alkalinity, chloride, and nitrate, suggesting localized contamination from natural and anthropogenic sources. Piper diagram analysis reveals Ca²⁺-Mg²⁺-HCO₃− dominance, pointing to carbonate rock dissolution, with some influence from agricultural and industrial activities. WQI classification categorized 76% of samples as fair to excellent, whereas 24% were marginal to poor. A heatmap analysis highlighted an improvement in water quality after 2012, though water from some stations remained persistently poor. Quantum geographic information system-based spatial mapping using the inverse distance weighting technique effectively visualized pollution hotspots and safe water zones. In conclusion, findings from the study underscore the need for regular monitoring, pollution control, advanced treatment methods, and sustainable groundwater management to ensure safe drinking water.