Monitoring of groundwater chemistry in terms of physical and chemical parameters of Gajraula, a semi-urbanized town of North India

•Shallow hand pumps were more contaminated than deep bore hole pumps.•Contamination levels were higher during summers.•TDS, NO3-, BOD, Ca2+, Fe and Pb concentrations exceeded their desirable limits.•The pollution load is influenced by the effluents of industrial, domestic and agriculture sectors.•Long term surveillance of water system should be carried out. Groundwater happens to be a major source of drinking water for urban and rural India. With rapid growth in industrial sector, the shallow groundwater regime has become more vulnerable to industrial contamination and human activity. In this study, the drinking water quality of Gajraula and its suburbs, a semi-urbanized town of northern India, was assessed. The water samples from pre-identified 14 wells with different depths were analyzed for 2years, i.e. 2008 and 2009. The samples were taken thrice a year in May (summers), August (monsoon) and December (winters). The compiled results were compared with recommended values of World Health Organization (WHO) and Bureau of Indian Standards (BIS) for drinking water. The analysis showed that concentration levels of TDS, BOD, NO3- and Ca2+ exceeded the desirable limits of WHO and BIS in certain wells. The levels of trace metals Fe and Pb exceeded the limits in almost all the wells, while pH, Cl−, SO42-, Mg2+, Zn, Cr and Ni were well within the limits. The contamination levels in most cases were higher during summers as compared to monsoon and winters, which may be due to high build-up of dissolved solids. The quality of water from shallow hand pumps in vicinity to industries were unsuitable for human consumption as compared to public deep bore wells. Agro-chemicals, irrigation by effluent discharge and wastewater from commercial cum residential area were the main sources of groundwater pollution. A study based on long-term surveillance of water systems, incorporating individual exposure assessment of users of private wells, should be considered for a lasting solution.