Why do we really need to drink 1.5 L/8 glasses (*) a day ?

Water is essential and vital to human life and involved in practically all functions of the human body. Water inputs should match water outputs. Plain water should be THE choice for daily hydration as part of a healthy lifestyle.

(*)Glass of 200ml for a healthy sedentary adult living in a temperate climate.


Foods and beverages both contribute to total water intake. Nevertheless, the water that we get from food is not sufficient to maintain the water balance (Jequier, 2010). The European Food Safety Authority (EFSA) states that intake of water is predominantly through consumption of drinking water and beverages (80%) plus water contained in food (20%) - EFSA, 2010.

On average, a healthy sedentary adult living in a temperate climate needs to drink 1.5L a day (Jequier, 2010)(**).

Recommendations such as drink 8 glasses(*)/times of water a day, aim at providing easy guidance for consumers to follow in order to reach the daily recommended intake of water.

Juices or sugar-sweetened beverages can be drunk occasionally but not all day long for daily hydration purposes as they add calories, which may impact health when over consumed. As water has zero sugar and no calories, water should be THE choice for healthier hydration.

(*) Glass of 200ml for a healthy sedentary adult living in a temperate climate
(**) For an adult basis (Jequier, 2010 - Department of Physiology, University of Lausanne, Pully, Switzerland)

infography new born adult senior percentage of water in the body

Did you know?

In adults, the body is about 60% water (Jequier, 2010). Mild dehydration may occur when only one per cent of body weight is lost due to insufficient water intake and may be accompanied by common symptoms: increased heart rate, decreased blood volume, headaches, dry or sticky mouth, increased thirst, sleepiness or tiredness (Mayo Clinic, 2015). Research shows that losses of two per cent or more can reduce cognitive (mental) performance (Grandjean AC & Grandjean NR, 2007).