Average daily urine output in a young person with well functioning kidneys is usually around 1.5 litres. Amount of daily fluid intake should approximately account for daily fluid losses predominantly via urine (1.5 litres) and remaining losses of fluid via sweating and respiration (0.5-0.7 litres per day). Hence, one should be consuming over 1.8-2 litres of fluid on a daily basis, the amount of intake fluctuating depending upon the weather conditions and level of activity. Of the 2 litres of daily requirement, over 20% of fluid requirement is met by common food we all consume. So the net amount of fluid left to be taken in is around 1.2-1.4 litres.