[en] To assess the quality of drinking water in respect to the content of radioactivity, usually is carried out an screening program in the locations of interest, that program consist in pick representative samples of drinking water from the wells in that locations, water samples are analyzed to measuring the gross alpha/beta radioactivity by a low background proportional counter or a liquid scintillation system. When some sample exceeds the normative limit then it must be known which radionuclides are in that sample. Expected radionuclides in water are the NORM (normal occurring radioactive material) from the natural radioactive chains. ²²⁶Ra is frequently present in drinking water and is one of most important radionuclide because its 'radiotoxicity', the WHO recommends a reference level for ²²⁶Ra of 1 Bq/L (the dose coefficient for ²²⁶Ra is 2.8 x 10^-7 Sv/Bq). From a national program of drinking water screening in the Mexican Republic, the samples that exceeded the national normative limits were picked again in the same well and analyzed by LS (liquid Scintillation), using the method of two phases with a not water miscible scintillator cocktail. Results of concentrations of ²²⁶Ra from drinking water are presented. In general the content of ²²⁶Ra in drinking water samples was lower that the guide values recommended for the WHO. (author)