Assessment of physicochemical quality and microbiological safety of jardrinking water marketed in Dhaka City, Bangladesh

Safe drinking water is necessary for optimum health, but a sufficient supply of safe drinking water is challenging in the twentieth century, particularly in highly populated cities like Dhaka. Due to the lack of fresh natural resources of potable water and the higher price of the commercially marketed mineral water bottle, many consumers prefer relatively lower-cost jar drinking water. However, the physicochemical properties and the safety of these jar-drinking waters are largely unknown. This study aimed to assess the physicochemical characteristics and microbiological safety of jar drinking water marketed in Dhaka City. Water samples from fifty different jar water sellers were collected and examined for different chemical quality parameters and microbiological safety using standard procedures and all test results were compared to water quality standards provided by the World Health Organization (WHO) and Bangladesh Standard and Testing Institution (BSTI). Heterotrophic plate count and coliform count were performed on different agar media and biochemical experiments were performed for the characterization of bacterial isolates. This research found that the total hardness, pH, total dissolved solids, electrical conductivity, and chloride content of the majority of the water samples were determined to be within acceptable limits. However, a large number of samples (88%) were found to be above the acceptable range for calcium and magnesium hardness, and approximately 33% of samples had greater levels of inorganic iron than the recommended limit. A total of 34 (68%) out of 50 samples exceeded the safety limit of heterotrophic bacteria whereas a total of 18 (36%) samples were found contaminated with coliform bacteria (ranges 3 to 29 CFU/100 mL). Biochemical experiments revealed another concerning fact, 14% of water samples were found positive for Escherichia coli and 6% was Salmonella spp. The findings of the study showed that the majority of the jar drinking water samples obtained throughout Dhaka City was not safe as per the standard provided by the WHO and/or BSTI. Therefore, these jar drinking waters can be a source of significant public health threat.