Water has numerous roles in the human body:
- building material
- reaction medium and reactant
- carrier for nutrients and waste products
- lubricant and shock absorber
The regulation of water balance is very precise, as a loss of 1% of body water is usually compensated within 24 hours.
Healthy adults regulate water balance with precision, but young infants and elderly people are at greater risk of dehydration.
Dehydration can affect consciousness and can induce speech incoherence, extremity weakness, hypotonia of ocular globes, orthostatic hypotension and tachycardia.
Human water requirements are not based on a minimal intake because it might lead to a water deficit due to numerous factors that modify water needs (climate, physical activity, diet and so on). On an average, a sedentary adult should drink 1.5 l of water per day, as water is the only liquid nutrient that is really essential for body hydration.
"Water" is a song which opened the Eurovision Song Contest in 2007. The singers explained the title: "Our folklore is like water. We've chosen this title "Water", because in Bulgarian folklore there are very slow beautiful songs, which are like a lake. But we also have songs, with very fast rhythm which are like a waterfall. And my wish is this song to be like "Water", a gasp of fresh air, for the human spirit and soul. When we recorded the promo video of this song, they poured lots of rain on us, and I felt purified. I want everyone, who hears this song to feel the same way- liberated. This is a very positive song! I'm sure that people will feel it!"
Water as an essential nutrient: the physiological basis of hydration. E Jéquier1 and F Constant2. European Journal of Clinical Nutrition (2010) 64, 115–123; doi:10.1038/ejcn.2009.111; published online 2 September 2009.