As much as 70% of body weight is water, and as much as 70% of earth is covered with water bodies; Is not it? There is some simile. Water is lost from body through invisible ways and visible ways.<ul><li>Visible Loss; <ol><li>Through faeces</li><li>Urine</li>and <li>Sweat</li></ol></ul><ul><li>Invisible loss: <ol><li>Through Respiration</li></ol></ul>
So, one should pass urine of about 1.5 litres/day to wash out most of the waste products of body metabolism. Both visible and invisible loss of water depend on the climatic conditions. if one feels thirsty, that means there is Ist degree dehydration i.e. about 5-10% of water is already lost from body. One must drink water frequently so that he/she does not feel thirsty. Drinking water after the thirst, only covers the loss to some extent.
So, one should be free to drink water before thirsty feeling comes up and drink so as to pass at least 1.5 to 2 litres of urine per day to stay healthy. That will be around 2.5 litres to 4 litres per day depending on the climatic conditions.
Excessive water drinking is also bad; causes, what is called water intoxication.