How much water do you drink each day? Doctors and nutritionists tell us to drink at least 8 glasses of water each day. Do you know why?

About 60% of our bodies are made up of water. This picture shows how much of us would be water if we were shaped like pies (fig.1 pie chart). People can survive for many weeks without eating any food (though they probably don't feel very well), but will die after only a few days without water.

Where is all the water in your body? Everywhere! Muscle is about 75% water by weight. Fat tissue is about 25% water. Even your bones are more than 20% water by weight. Your bodily fluids, like blood, snot, pee, sweat, and tears, are also made up in part by water.

What does all the water do in your body? For one, it helps keep your body's temperature under control. When you get hot, you release water onto your skin (sweat). Sweat uses heat from your body to dry up (evaporate). We also keep cool by breathing out (exhaling) water vapor from our lungs.

Water is also your body's lubricant -- it keeps your eyeballs moist and "oils" all your joints. You may notice that when the weather is really dry or hot your mouth and skin feel dry -- drinking water gives almost instant relief!

Another important function of water in our bodies is as a shock absorber. Our brains and spinal cords are protected by water. Water cushions keep your brain from getting bruised when you do things like jump or shake your head.

The average person needs to drink at least eight glasses of water a day. People who live in really hot or dry places, and people who exercise and therefore sweat a lot will need to drink more. Though drinking plain water works just fine, you can also get your water needs satisfied by drinking juice, milk, and other beverages (but not coffee, tea, or alcohol -- they remove water from your system). Fruits and vegetables also count as water providers because they are about 80% water by weight.

So, help your body be the best it can be and keep the water flowing!