A procedure for sequential determination of isotopes of polonium, radium, and uranium from the same aliquot of a water sample has been standardized. The important step in the procedure is coprecipitation of radionuclides of interest with calcium phosphate followed by auto deposition of polonium on a silver planchette. Radium is precipitated with barium nitrate under ice cold condition. Uranium isotopes are separated using ion exchange resin. ¹³³Ba was used for estimating the chemical yield of radium assuming that these elements have similar chemical behavior. ²³²U and ²⁰⁹Po were used for estimating the chemical yield of ²³⁴ U, ²³⁸ U, and ²¹⁰ Po, respectively. Seven water samples were analyzed and the average chemical yield for polonium, barium, and uranium were obtained at 71.8, 65, and 51.6%, respectively. The standardized procedure is being used in the analysis of these natural radionuclides in packaged drinking water.