This book covered a broad spectrum study of arsenic contamination in drinking and irrigated water and its impact on food crops and local community lived in arsenic affected areas of Pakistan. Speciation of arsenic in water samples was carried out by advance preconcentration methods for trace analysis. It is a first attempt to elucidate the chemical fractionation of geochemical bonded fractions of arsenic in soil and sediment. Moreover, the translocation of arsenic from growing media (irrigation water and soil)to local agricultural crops (grain crops and vegetables)was addressed well. The impact of arsenic of human was also studied using scalp hair samples as biomarker and detail study of risk assessment was performed. At the end the removal of arsenic from water was done by using biomass taken from a local plant (Acacia nilotica). The effects of various parameters vis, pH, biosorbent dosage, temperature and exposure time for bio-sorption of As were investigated in detail. The complete characterization, chemical equilibrium, kinetic and thermodynamic study was carried out. The removal of arsenic by biomass of A. nilotica was > 95%.