Chemical and Microbial Risk Assessment of Drinking Water in Faria Catchment

Risk assessment is a process intended to estimate the risk to a given target, following exposure to a particular agent. The process begins with problem formulation and includes four fundamental steps: 1) hazard identification, 2) toxicity assessment, 3) exposure assessment 4) risk characterization. This thesis aims at describing the potential risk of chemicals and microbes to the general population of the Faria catchment, estimating the potential future risk, and proposing a risk management options to mitigate hazards for chemical and microbial contents of the catchment. Drinking water data for chemicals, microbes, and some physical water properties for some selected wells and springs in the Faria catchment, were obtained from WESI in the context of UWIRA project. The water quality data were compared with local and international drinking water standards. The results showed that all the chemical concentrations are below the Palestinian and EPA maximum contamination levels, while the turbidity and fecal coliform (FC) are above both levels. Structured interviews have been conducted through eleven villages located within the catchment, in order to determine the sources of exposure and the intakes of the chemicals, which helped to identify the parameters for the risk formulas. In order to estimate the chemical and microbial risks in the Faria catchment, mainly for drinking water, the fundamental steps of risk assessment have been conducted. Toxicity assessment resulted in screening and ranking the most common chemicals and microbes that are tested in drinking water resources which are, the major ions (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, PO43-, and NO3-), total hardness, and the total FC. The exposure assessment described the levels of exposure using chronic daily intake equations for various pathways. All data collected from exposure and toxicity assessments were used in risk characterization step. Using an online QMRA Wiki analyst for microbial risk characterization, the risk probability results of E.coli doses indicates that at least one person out of one thousand people, will get sick by the presence of E.coli in the drinking water of the catchment resources. For chemical risk characterization, hazard index was used to find the potential toxicity for adult males, adult females, and children. The results showed that, each parameter individually may not cause non-carcinogen toxicity, but may collectively cause adverse health effects due to bioaccumulation of long-term exposure to chemicals. Potential future risk of some heavy metals and organic compound of Faria stream was estimated using chemical risk formulas. The results indicated that there is a great potential of non-carcinogen toxicity if these pollutants have been proven to reach the catchment drinking water resources. Risk management practices such as, installing sanitation systems to provide treatment and proper disposal of wastewater for all the villages that use cesspits, and continuous monitoring of chemicals and microbes of the catchment water resources, were recommended to mitigate any potential risk caused by the presence of chemicals and microbes in the drinking water, and to enhance the quality of the catchment's water resources.