Heat waves can be deadly for humans, animals and vegetation. According to the cumulative estimates by the RKI (Robert Koch Institute) in Germany up until 2026-7-26 there were 11.900 deaths within the confidence interval between 10.700 to 13.100 of the estimates. About 6.000 of the people who died due to the heat waves were aged 85+. 1.140 were attributed to persons younger than 65. Chronological age appears to be a significant factor as frequently chronic diseases accumulate in older individuals as well as poly-pharmacy. Hydration levels and deficiencies are associated with the increased mortality, but we have few or no precise measures of hydration readily available for people before it becomes an emergency (cognitive impairments). We know a lot about precision medicine. However, precision hydration for people remains rather arbitrary.































