Concentration of natural radionuclides in raw water and packaged drinking water and the effect of water treatment

The raw water (RW) samples collected from natural sources are subjected to water treatment process, including reverse osmosis (RO), and are packed in bottles as packaged drinking water (PDW). Raw water (21 samples) taken from deep wells of Chennai and Secunderabad which are used in the production of PDW, were analysed for 234U, 235U, 238U, 226Ra, 228Ra and 210Pb activity concentrations. Activity Concentrations of 234U, 235U, 238U, 226Ra, 228Ra, 210Pb and 210Po in PDW were also analysed. The mean activity concentrations of 234U, 235U, 238U, 226Ra, 228Ra and 210Pb in RW at Chennai were 12.1, ≤1.3, 7.1, 2.6, 27.5, and 16.3 mBq/L respectively. The mean activity concentrations of 234U, 235U, 238U, 226Ra, 228Ra and 210Pb in RW at Secunderabad were found to be 40.9, 1.7, 41.5 84.5, 100.1, and 17.0 mBq/L respectively. The mean concentrations of 234U, 235U, 238U, 226Ra, 228Ra, 210Pb and 210Po in PDW at Chennai were found to be ≤1.3, ≤1.3, ≤1.3, ≤0.2, ≤1.7, 28.0 and 1.2 mBq/L at Secunderabad were found to be ≤1.3, ≤1.3, 1.7, 4.3, 5.0 and 28.1 mBq/L. The study indicated a considerable reduction in the concentration of natural radionuclides due to water treatment. The reduction ratios of RW to PDW for 234U, 238U, 226Ra, 228Ra were 97, 96, 94 and 95%. In case of 210Pb, the PDW showed higher concentration of 210Pb than RW. This was due to its in growth from 222Rn which was not removed in the RO process.