AbstractA method for the trace‐level determination of bromate in raw and drinking water is reported. The procedure combines the quantitation of bromate by ion chromatography with a concentration step which in the main is composed of an unselective enrichment of all water constituents by means of a rotatory evaporator and a selective removal of the chloride ions. With this method, the reliable determination of bromate in raw and drinking waters is possible down to concentrations of at least 1 μg/L.The method is used for systematic examinations in several German waterworks which use ozone for the preparation of drinking water. The resulting data clearly prove that during the ozonation of bromide‐containing waters, bromate is produced, whereby the concentration of bromate in the ozonated raw water can exceed 10 μg/L. Some correlations between the amount of bromate and the respective conditions of ozonation are pointe