Everyone needs to drink a different amount of water, said dietitian Juliette Kellow and nutritionist Dr Sarah Brewer.
Your daily requirements depend on your weight, age, gender, level of activity, and the climate you live in, they said.
But women should be drinking around two litres of water every day, and two and a half litres for men.
During a normal day, a person loses about two litres of water just through breathing, sweat and other bodily functions.
Even while asleep, we can lose over one kilogram (2.2 pounds) of water-weight not just through sweating, but respiration as well. Even air conditioning has drying effects on our body.
There are a number of evidence-based health benefits of drinking plenty of water, including maximising physical performance; optimizing energy levels and mood; and aiding digestion and elimination.