The present work shows the development of five radiochemical methods in order to determine Ra226 in river waters for human consumption, through gamma spectrometry. These methods are used in order to obtain this radionuclide as Ba(Ra)S04. The method tested was found to be the most appropriate due to its lower cost, high radiochemical yield obtained (83.53 %) on average and the obtained results show smaller variability. This standardized method is applied to water samples of the Chillon river, outcoming an activity of 0.1526 Bq/L. Assuming inhabitants of Huarangal Valley consumme 2 liters of this river water daily. The annual ingest is about 111.398 Bq on average, which constitutes the 1.58 % of the allowed radioactivity limit given by the regulation on sanitary protection against ionizing radiation. Furthermore physical chemical analysis in waters of the Chillon river were performed. The ...