[en] The steps required to measure radon in water using liquid scintillation counting are presented. The steps, which are explained in detail, are: sampling, scintillation counter operation, analysis of the counts, calculation of the concentration, and the preparation of standards. The process of testing water for radon concentrations can be summarized into three steps: (1) preparation of water sample vials; (2) counting the activity of the vials using a liquid scintillation counter; and (3) converting the counts per minute into picocuries per liter. The operation of the liquid scintillation counter involves several steps, which include: calibrating the gain, setting up the discrimination windows, adjusting the time of counting, loading a set of samples and standards, and calculating and reporting the results. It is concluded that the process of testing water for radon gas is an effective means of determining if the water poses a significant source of indoor air radon and a significant health threat. A thorough understanding of radon gas, its progenies health hazards, and methods of infiltration facilitate a more accurate analysis of individual homes. 6 refs., 2 figs., 1 tab