Re: a question to qualified doctors........
1- There is no set amount of water need by a person. *It varies *(even in in healthy people) with activity, exercise, environmental and body temperature, consumption of food and other kind of drinks such a cola beverages, smoking and even body size.
2- With the same token, 470 ml is too low (less than two glasses a day assuming one glass is 250 ml) for a good size adult. Perhaps we need to differentiate between consumption required and actual body needs.
Those people who are placed on water restriction due to some diseases, even up to 800cc or a liter a day are psychologically miserable.
3-If one is otherwise healthy then it does not matter how much water is consumed.
All the extra water will just go out of body. A good kidney will dump it anyway. Off course it will also dump salt with it since salt/minerals follow water. (Stay close to bathroom if you do. :-)
Water poisoning can only happen if someone drinks liters of water in very short time. Headache, blurred vision, shortness of breath are common with that.
4- A correct amount of water consumption based on body needs does keep skin healthy, moist, with less wrinkles, heart, kidneys and blood viscosity.
Also a good amount of blood acidity/alkalinity (pH balance) depends on water balance. Dehydration causes high pH of blood (contraction alkalosis)
5- Thirst is really a good way to keep body water balance but we do tend to suppress thirst if we are busy or even have too much thirst in stress or anxiety or when someone takes certain meds. like benedryl (dry mouth). So thirst is not related to body water needs 100 percent.