Maybe you’ve heard this factoid before: The body can last weeks without food, but only days without water.

In general, human beings are primarily composed of H2O. Water is of major importance because it regulates a number of essential functions in the body. That said, depending on age and gender, each of us is composed of different percentages of water, according to Jeffrey Utz, MD, a pediatric neuroscientist, who posted this information on Madsci Network online. What’s more, each day we must consume a certain amount of water to survive.

Adult males need about 3 liters of water each day while adult females need 2.2 liters each day, according to the U.S. Geological Survey. This is because water is vital to the life of each cell in our bodies. Water also regulates our internal body temperature when we sweat and breathe, breaks down and transports the nutrients in food through the bloodstream, and flushes waste out of our bodies.

Also, water helps us produce saliva for digestion, acts as a shock absorber for our organs and lubricates our joints. No wonder so many people call this clear and colorless liquid a basic necessity that’s really the “stuff of life.”