Water quality fact sheet: Iodine

Most trace elements in drinking water are of concern from a public health point of view because of potential for excess above recommended limits. However, some trace elements are essential to health and so are required to be present at certain concentrations in drinking water or food. Iodine is one such essential element. Deficiency in dietary iodine can lead to a number of iodine-deficiency disorders (IDDs) in humans. No regulations or recommendations are placed on concentrations of iodine in drinking water because such standards are imposed to regulate upper rather than lower limits. Iodine may also be potentially detrimental to health at high concentrations, but the element usually behaves in a similar way to chlorine in nature and hence iodine-rich waters are likely to be rendered unfit for potable use due to high salinity before iodine becomes a significant problem.