The recommendation that drinking 8 glasses of water a day is good for you ... is a myth. There is no data supporting this recommendation. In fact, we cannot find where this recommendation originated.
No two people are alike. No two people eat the same. They don't sweat the same. So why should they drink the same amount (8 glasses of water a day)?
The appropriate amount of fluid intake depends upon your specific situation. Those who exercise frequently or who have kidney stones should drink more. If you tend to retain fluid (edema) or need medications to urinate more (diuretics), then you should drink less.
In summary, there is no standard prescription for fluid intake. Not enough water is not good for some (e.g. dehydration) but too much water is harmful to many (e.g. fluid overload, edema, hyponatremia).
Questions or have problems with the above? Come talk to us at HKC.