An Analysis of Health Risk Associated with Urban Water Supply in Bangladesh

Abstract

Water, a vital resource for the survival of human species, has the potential to be a destructive force with if contaminated significantly. The trend of population immigration towards large cities and rapid economic growth has led to necessity of modern, well maintained, centralized water distribution systems. However, aging of the system, overstress and poor maintenance of distribution system leads to degradation of water quality below acceptable levels within the supply network. These contaminations occurs due to various reasons including but not exclusive to failure to maintain proper disinfectant residual, low pipeline water pressure, intermittent water supply, excessive network leakages, corrosion of parts and inadequate sewage disposal. In the length of this study, two secondary data sources have been used obtain water quality parameters for two southwestern areas of Bangladesh, Khulna City Corporation (KCC) and Jessore Pourashava (JP) to establish the water quality situation in these areas and to deduce the probable flaws in the supply network that is affecting specific types of contaminations. The quantitative assessment was done by probabilistic comparison among physical, chemical and microbial parameters like – turbidity, color, pH, conductivity, TDS, Total Coliform, E. Coli etc. Quantitative Health Risk Assessment (QHRA) model was used to evaluate present scenario of disease burden based on microbial parameters. This assessment was also compared between KCC and JP to identify severity of disease proneness. It was observed that among 96 sample data from JP and 138 sample data from KCC, all show acceptable level of turbidity in terms of Bangladeshi standards. But for color parameter, 77% of KCC samples and 27% of JP samples exceeded limit. For chemical parameters, all samples from JP was acceptable for pH, Electrical Conductivity, Chloride, TDS and 7% and 32% samples exceeded limit for hardness and alkalinity as CaCO3 respectively. For T.C. and E.coli, 83% and 79% samples exceeded allowable limit respectively. In KCC, above 70% samples exceed allowable limit for Electrical Conductivity, and for chloride and TDS, 24% and 15% samples, respectively, exceeded allowable limit. For T.C. and E.coli, 100% and 77% samples correspondingly are beyond 6 permissible limits. From the QHRA analysis it is seen that the disease burden due to the high values of microbial parameters exceed the guideline value (GV) which signifies that the water quality of these two water supply networks are not in good condition.