Study of 222Rn concentrations in drinking water in the north-eastern hydroregions of Poland

This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells located in the north-eastern part of Poland. The measurements were carried out on 643 samples using a liquid scintillation method. The mean value was found to be 5262 Bq m−3 with a maximum of 38347 Bq m−3. The samples were obtained from different water-bearing levels, i.e. surface water, deep borehole water and well water and have respective mean values of 3398, 5178 and 6155 Bq m−3. In 57 water samples, a guideline maximum level of 11 000 Bq m−3 was found to be exceeded. The observed radon concentration in water can contribute to a 2% increase in indoor radon concentration.