Water regulation in the human body is primarily controlled by the kidneys, with younger people having a broader range of urine concentration ability (40-1400 mOsm/kg) compared to elderly individuals (92-700 mOsm/kg). The body requires 2.5-3 liters of water daily under normal conditions, which can increase to 6 liters in extreme heat. Even mild dehydration (2-2.6% body weight) can impair cognitive function and physical performance. The article highlights that elderly and children are particularly vulnerable to dehydration - elderly due to reduced thirst sensitivity and kidney efficiency, while children due to their higher surface-area-to-body-mass ratio. An interesting finding from a German school study showed that providing water dispensers and education reduced diabetes risk by 31% in children. The article also debunks the myth that increased water intake significantly improves skin hydration and reduces wrinkles.