Within this work, the activity concentrations of uranium isotopes (234U, 235U, and 238U) were analyzed in some of the popular and regularly consumed Hungarian mineral-, spring-, therapeutic waters and tap waters.
Samples were selected randomly and were taken from different regions of Hungary (Balaton Upland, Bükk Mountain, Somogy Hills,
Mezőföld, and Lake Hévíz). Concentration (mBq L−1) of 234U, 235U, and 238U in the waters varied from 1.1 to 685.2, from <0.3 to 7.9, and from 0.8 to 231.6 respectively. In general, the highest uranium
concentrations were measured in spring waters, while the lowest were found in tap waters. In most cases radioactive disequilibrium
was observed between uranium isotopes (234U and 238U). The activity ratio between 234U and 238U varies from 0.57 to 4.97. The calculated doses for the analyzed samples of spring water are in the range 0.07–32.39 μSv
year−1 with an average 4.32 μSv year−1. This is well below the 100 μSv year−1 reference level of the committed effective dose recommended by WHO and the EU Council. The other naturally occurring alpha
emitting radionuclides (226Ra and 210Po) will be analyzed later to complete the dose assessment. This study provides preliminary information for consumers and
authorities about their internal radiological exposure risk due to annual intake of uranium isotopes via water consumption.