Cosmogenic radio-sulphur (^(35)S) is applicable as aqueous environmental tracer for investigating sub-yearly groundwater residence times. For the purpose ^(35)SO(4) has to be extracted from large-volume water samples (ca. 20 l) and measured by liquid scintillation counting (LSC). Publications that discuss sample preparation approaches focus on waters with low or moderate sulphate concentrations based on sulphate extraction using an ion-exchange resin. However, sulphate extraction by …