Mist rising silently off a still lake at dawn. Sheeting rain pounding your windshield while you drive. The drip of the kitchen faucet that drives you crazy and the crisp, cold mouthful of water you gulp after a brisk walk.

Water. It can be soothing, scary and annoying, but above all, it is essential to life. Your life and mine.
Up to 75 percent of our body weight is made up of water. It is inside our body cells ("intracellular") as well as in the fluid that bathes those cells ("extracellular"). Without enough water we start to "dehydrate," or have more water leaving the body than the amount being taken in. When we lose enough water or dehydrate to a certain amount, we can die.

So, how much water do we need each day? The National Institute of Medicine recommends that women drink 9 cups of water a day; men should consume 13 cups. But probably a better guide is to take in enough fluids daily to urinate four times during the day and to have a urine that is light yellow in color.

We all lose a minimum of 6 and a half cups of fluid daily just through our sweat, saliva, stomach juices and urine/stool. The amount we need to replace our daily losses actually depends on our age, weight, environment and activity level. Generally, the more a person weighs, the greater their fluid needs. If we live in a warm environment, we tend to lose more in sweat than if the temperature remains cool. Similarly, if a person is more physically active they will lose more water through sweating.

When it comes to meeting your body's fluid needs, water is the best. That said, it's good to remember that almost everything we eat or drink contains some water and can count towards your daily water requirement. Beverages typically have a higher amount of water, but so do foods like soup and Italian ice. We almost unconsciously reach for more hydrating food choices when our bodies need more fluids.

Aside from satisfying our thirst, what else can water do for us?

--- Keep you mentally sharper -- your brain is about 78 percent water. If you are low on water, it can impair your mental function.
--- Relieve headache pain -- drink one to two glasses of water before trying a pain relieve for your head pain. Headaches are a common sign of dehydration.
--- Energy boost -- remember those body cells? They rely on water to keep producing energy. Maintaining good hydration keeps you more energized.
--- Lower arthritis pain -- water is a key component of the fluids in joints. With less water, there is less lubrication, so more potential for pain.
--- Burn more calories -- there is a short-term calorie-burning effect to drinking water. Drinking 1 to 2 glasses of water before meals can also make you feel fuller so you don't eat as much.
So, when you feel thirsty, pay attention to what your body's trying to tell you. Pick up a glass of water and enjoy. Don't hesitate to hydrate!

Cathie Brookhart is a clinical/outpatient dietitian at Gettysburg Hospital. Healthy Helpings is a column written by nutritionists in York and Adams counties.