Assessment of groundwater quality of Dehradun Valley, Uttarakhand, India, for drinking purposes using multivariate statistical techniques

Access to safe drinking water for the public is of utmost concern in developing nations to achieve sustainable development. The usage of groundwater for drinking purposes is well known on account of its less susceptibility to contamination; it is thus considered essential to examine the quality of water that is intended for public supply. This research assesses the groundwater quality of Dehradun Valley of outer Himalayas, Uttarakhand, India, for drinking purpose using geographical information system and multivariate statistical tools. The results from the research revealed groundwater of the study area dominated by calcium–magnesium–bicarbonate hydro-chemical facies, which show the occurrence of limestone/dolomite, magnesite, talc rock types in the geology of the region, controlling the hydrogeochemistry of the groundwater. Few water samples falling under the ‘mixed type’ zone of the plotted Piper diagram reflect influence of anthropogenic sources of pollution. The groundwater quality was also evaluated using the water quality index, that grouped 96% of tested water sources for having ‘excellent’ to ‘good’ water quality, whereas 4% fall under ‘fair’ category, which were not fit for consumption purposes. The physico-chemical investigations showed turbidity and iron concentration at few sources, exceeding the limits of Bureau of Indian Standards drinking water specifications. The multivariate statistical techniques (Pearson Correlation Analysis, Principal Component Analysis and Hierarchical cluster analysis) suggest the rock–water interactions and corrosion of underground pipelines and metal surfaces influence the groundwater quality in the study area. The study suggests to undertake regular maintenance and repair works of damaged underground water supply machinery, to consistently monitor and understand the groundwater characteristics of the region and identify the associated factors which can impact its quality, so as to ensure safe public water supply and to manage the groundwater sources sustainably in the study area.