Examining the Influence of Desalinated Water on Iodine Concentration in Tap Water in Israel

In Israel, desalinated water is a major source of drinking water, blended with water from local wells and Lake Kinneret. Studies have shown that iodine concentrations in the water provided by authorities may not accurately reflect levels reaching end-users. We analyzed the iodine content in 21 tap water and several natural water samples collected from different localities across Israel during May-June 2021, using an improved method of ICP-MS. Our results showed that it is possible to distinguish between sample groups based on iodine concentration, water hardness, and Ca/Mg ratio. The median values for four groups of tap waters ranged from 0.3 to 12.3 g I L-1, which is lower than the iodine concentration in Israeli tap water reported previously by other researchers. Calculations based on typical consumption suggest that the water can provide no more than 3.39% of the recommended dietary allowance level. Additionally, we also analyzed 13 samples of post-treated desalinated water from three of the largest Israeli desalination plants. The results indicate that these waters comply with industrial specifications but contain only trace concentrations of iodine and much less magnesium than recommended by different public health authorities for public consumption of drinking water.