Because of rigorous problems of water stress and water quality degradation, there is prime concern about groundwater quality all over the world. For south Asian countries especially India and Bangladesh, high levels of arsenic, nitrate, fluoride and salinity in groundwater have severe consequences to human health which trigger us to conduct this work. This study is an effort to trace the factors responsible for arsenic enrichment in groundwater of the two major states (Bihar and Uttar Pradesh) in middle Gangetic Plain of India through major ion chemistry, arsenic speciation and multivariate statistical techniques. Weathering of carbonate and silicate minerals, surface water interactions, ion exchange, redox processes, and anthropogenic activities are responsible for groundwater contamination with high concentrations of cations, anions and arsenic in the groundwater. This study is vital considering that groundwater is the exclusive source of drinking water in the region and not only makes situation alarming but also calls for immediate attention.