Water desalination has been extensively developed in Israel, particularly in the last decade. The desalination process provides fresh water that typically lacks minerals, and among these are ions that are essential to human health and/or to agricultural production, such as Mg. We analyzed 28 tap water samples originating from different cities across Israel to document their concentrations of Mg and other elements. The data from this survey (summer 2016) were compared with the results of similar observations conducted in 2008. Regarding toxic elements, tap water across Israel does not pose any health risk for consumers and may be used as drinking water without any household pretreatment. This condition has not changed since 2008. However, the problem of Mg deficiency due to the use of desalinated water was observed in about half of the sampling locations in 2016, whereas no Mg deficiency had been detected in 2008. Moreover, household filtration of tap water prior to consumption as drinking water may worsen the situation due to the Mg status resulting from rejection of this ion; this could be harmful to the consumer, particularly under prolonged exposure.