Question: how much water to drink in a day in litres according to weight?
Answer: As a general rule, you can use this simple calculation. Water (in litres) to drink a day = Your Weight (in Kg) multiplied by 0.033. For example, if you are 60kg, you should drink about 2 litres of water every single day. At 90kg, you'll around about 3 litres of water.