Water is virtually everywhere,

from soil moisture and ice caps,

to the cells inside our own bodies.

Depending on factors like location,

fat index,

age,

and sex,

the average human is between 55-60% water.

At birth, human babies are even wetter.

Being 75% water, they are swimmingly similar to fish.

But their water composition drops to 65% by their first birthday.

So what role does water play in our bodies,

and how much do we actually need to drink to stay healthy?

The H20 in our bodies works to cushion and lubricate joints,

regulate temperature,

and to nourish the brain and spinal cord.

Water isn't only in our blood.

An adult's brain and heart are almost three quarters water.

That's roughly equivalent to the amount of moisture in a banana.

Lungs are more similar to an apple at 83%.

And even seemingly dry human bones are 31% water.

If we are essentially made of water,

and surrounded by water,

why do we still need to drink so much?

Well, each day we lose two to three liters through our sweat,

urine,

and bowel movements,

and even just from breathing.

While these functions are essential to our survival,

we need to compensate for the fluid loss.

Maintaining a balanced water level is essential to avoid dehydration

or over-hydration,

both of which can have devastating effects on overall health.

At first detection of low water levels,

sensory receptors in the brain's hypothalamus

signal the release of antidiuretic hormone.

When it reached the kidneys, it creates aquaporins,

special channels that enable blood to absorb and retain more water,

leading to concentrated, dark urine.