The mast suitable way of determination iodine-deficiency is to measure iodine concentrations in water and urine. For this reason, a method that can determine iodide concentrations in drinking water and suitable for routine analysis, is developed. Water samples have been collected from four Aegean localities: Izmir, Salihli, Odemis and Tire situated in the western Turkey. The method is based on substochiometric isotope dilution analysis. Iodide concentrations vary within 9.86-85.14 mu g/l ranges in the analyzed samples. Mean value is 44.92+/-22.07 mu g/l.