Detection of Hazardous Contaminants in Ground Water Resources: An Alarming Situation for Public Health in Karachi, Pakistan

Due to industrialization and over population, surface water resources are out of reach from many people so consumption of ground water is the only choice to overcome the water scarcity. Naturally, ground water is one of the significant and potable water resource but some geographical conditions and anthropogenic activities deteriorate the water quality and make it objectionable for drinking. This study was conducted to evaluate the ground water quality of Karachi, Pakistan. For this, 42 ground water samples were collected from different districts of Karachi and analyzed their physicochemical and microbiological characteristics and compared with both international (WHO) and national (SEQS) drinking water standards. Observations of the study declared that overall contamination (physicochemical and microbial) in the ground water samples of different districts of Karachi was as follow West (21%), South (20%), Central (17%), Malir (16%), Korangi (14%) and East (12%). Physical assessment of the study area declared that pH and turbidity of the ground water samples varies in the range of (6.54-7.9) and (0-1.01 NTU) which exist in the standard prescribed limit. Whereas, detection of chemical contaminants particularly TDS (457-12090 mg/L), hardness (118.8-3645 mg/L) and chloride (190-4918 mg/L) content in most of the samples were also exceed from the prescribed limit. Additionally, arsenic was abundantly present ranging from 3.52-13.63 mg/L in all collected samples of Karachi city while the concentration of cadmium (range: 0.0005-0.5012 mg/L) and lead (range: 0.201-1.817 mg/L) were also high in few samples, from the permissible limit of drinking water. Microbial contamination was also detected in which coliforms were present in the range of 0-150 CFU/100mL, which also unfit the water quality. This deteriorated ground water quality of Karachi can be improved by maintenance of proper sanitary conditions of the communities and implementation of water treatments, otherwise consumption of such water may develop serious health related consequences in the consumers.