How much water should you drink a day?

how much water should you drink a day

Water is essential to the human body, which requires the maintenance of a delicate balance between water loss and water intake. Plain water is by far the best choice for daily hydration.

The body needs water

The body of a human adult is about 60% water(1). Water performs numerous critical physiological functions in the human body, including those of a solvent, a carrier for nutrients and waste products, a thermoregulatory and a lubricant. Staying properly hydrated is contributing to well-being.

Daily recommended intake

We take in water both from food and drink but the amount of water we get from food alone is not enough to maintain the body’s water balance(1). In fact, the European Food Safety Authority (EFSA) estimates that we take in 80% our water from beverages (including water itself) and only 20% from food(2).

Current understanding of the body’s very precise water balance regulation mechanisms allows experts to estimate that, on average a healthy sedentary adult living in a temperate climate needs to drink 1.5L (8 x 200 mL glasses) over the course of a day(1).

This is an average amount because, of course, fluid requirements vary depending on factors such as age, gender, phase of life (for example, pregnancy), physical activity level, climate and diet.

Why drinking water ?

Juices or sugar-sweetened beverages can be drunk occasionally, but not all day long for daily hydration purposes. They are full of calories, which may impact health when over consumed. Since it contains no sugar or calories, plain water should be THE choice for daily hydration.

Did you know

Mild dehydration may occur when only 1-2% of body weight is lost due to insufficient water intake. It may be accompanied by common symptoms such as headaches, dry or sticky mouth, thirst, sleepiness or tiredness(3). Research shows that mild dehydration can reduce cognitive (mental) as well as physical performance(4).


Sources: (1) Jequier E., Constant F., Cahiers de nutrition et de diététique, 2009; (2) European Food Safety Authority (EFSA), Scientific Opinion on Dietary Reference Values for Water. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). EFSA Journal 2010; 8(3): 1459; (3) Mayo Clinic, 2015; (4) Grandjean AC & Grandjean NR, dehydration and cognitive performance, 2007