The results of research on the application of the method of measurement of gross alpha-, beta-activity in water using the liquid scintillation counter (LSC) Quantulus 1220 are presented. Basic procedures of preparation and spectrometric measurement of aqueous samples were studied and performed. The detection efficiency of alpha-, beta-particles depending on quenching and the optimum alpha-, beta-radiation separation parameter for the method used were determined. Testing and validation of the technique was carried out on model solutions with different concentrations and composition of alpha- and beta-emitters, as well as by participating in interlaboratory comparisons. The results demonstrated that the use of LSS allows for a sufficiently fast and accurate estimation of the gross alpha- and beta-activity in water below the regulated limits without the use of labor-intensive sample preparation.