Benefits of Water
The human body, which is made up of between 55 and 75 percent water
(lean people have more water in their bodies because muscle holds
more water than fat), is in need of constant water replenishment.
lungs expel between two and four cups of water each day through
normal breathing - even more on a cold day. If your feet sweat,
there goes another cup of water. If you make half a dozen trips
to the bathroom during the day, that's six cups of water. If you
perspire, you expel about two cups of water (which doesn't include
A person would have to lose 10 percent of her body weight in fluids
to be considered dehydrated, but as little as two percent can affect
athletic performance, cause tiredness and dull critical thinking
abilities. Adequate water consumption can help lessen the chance
of kidney stones, keep joints lubricated, prevent and lessen the
severity of colds and flu and help prevent constipation.
Health benefits of water
Water is crucial to your health. It makes up, on average, 60 percent
of your body weight. Every system in your body depends on water.
Lack of water can lead to dehydration, a condition that occurs
when you don't have enough water in your body to carry on normal
functions. Even mild dehydration - as little as a 1 percent to 2
percent loss of your body weight - can sap your energy and make
you tired. Dehydration poses a particular health risk for the very
young and the very old. Signs and symptoms of dehydration include:
- Excessive thirst
- Dry mouth
- Little or no urination
- Muscle weakness
How much water do you need?
Every day you lose water through sweating - noticeable and unnoticeable
- exhaling, urinating and bowel movements. For your body to function
properly, you need to replace this water by consuming beverages
and foods that contain water. So how much water, or more precisely
fluid, do you need?
This isn't an easy question to answer. A healthy adult's daily
fluid intake can vary widely. Most people drink fluid to quench
thirst, to supply perceived water needs and "out of habit."
At least three approaches estimate total fluid (water) needs for
healthy, sedentary adults living in a temperate climate.
- Replacement approach. The average urine output for adults
is 1.5 liters a day. You lose close to an additional liter of
water a day through breathing, sweating and bowel movements. Food
usually accounts for 20 percent of your fluid intake, so you if
you consume 2 liters of water or other beverages a day (a little
more than 8 cups), along with your normal diet, you can replace
the lost fluids.
- Eight 8-ounce glasses of water a day. Another approach
to water intake is the "8 x 8 rule" - drink eight 8-ounce
glasses of water a day (about 1.9 liters). The rule could also
be stated, "drink eight 8-ounce glasses of fluid a day,"
as all fluids count toward the daily total. Though this approach
isn't supported by scientific evidence, many people use this basic
rule as a guideline for how much water and other fluids to drink.
- Dietary recommendations. The Institute of Medicine recommends
that men consume 3 liters (about 13 cups) of total beverages a
day and women consume 2.2 liters (about 9 cups) of total beverages
a day. These guidelines are based on national food surveys that
assessed people's average fluid intakes.
You can choose any of these fluid intake approaches to gauge your
fluid needs. But your current total fluid intake is probably OK
if you drink enough water to quench your thirst, produce a colorless
or slightly yellow normal amount of urine, and feel well.
Factors that influence water needs
You may need to modify total fluid intake from these recommended
amounts depending on several factors, including how active you are,
the climate, your health status, and if you're pregnant or breast-feeding.
- Exercise. If you exercise or engage in any activity that
makes you sweat, you'll need to drink extra water to compensate
for that fluid loss. Drink 2 cups of water two hours before a
long endurance event, for example, a marathon or half-marathon.
One to 2 cups of water is also adequate for shorter bouts of exercise.
During the activity, replenish fluids at regular intervals, and
continue drinking water or other fluids after you're finished.
During intense exercise involving significant sweating, for example,
during a marathon, sodium is lost in sweat, and you may need a
sports drink with sodium rather than just water.
- Environment. You need to drink additional water in hot
or humid weather to help lower your body temperature and to replace
what you lose through sweating. You may also need extra water
in cold weather if you sweat while wearing insulated clothing.
Heated, indoor air can cause your skin to lose moisture, increasing
your daily fluid requirements. And altitudes greater than 2,500
meters (8,200 feet) also can affect how much water your body needs.
Higher altitudes may trigger increased urination and more rapid
breathing, which uses up more of your fluid reserves.
- Illnesses or health conditions. Some signs and symptoms
of illnesses, such as fever, vomiting and diarrhea, cause your
body to lose extra fluids. To replace lost fluids, drink more
water or oral rehydration solutions (Gatorade, Powerade, CeraLyte,
others). When water loss can't be replaced orally, intravenous
water and electrolytes may be necessary. Increased water intake
is nearly always advised in people with urinary tract stones.
On the other hand, you may need to limit the amount of water you
drink if you have certain conditions that impair excretion of
water - such as heart failure and some types of kidney, liver,
adrenal and thyroid diseases.
- Pregnant or breast-feeding. Women who are pregnant or
breast-feeding need additional water to stay hydrated and to replenish
the fluids lost, especially when nursing. The Institute of Medicine
recommends that pregnant women drink 2.3 liters (nearly 10 cups)
of fluids a day and women who breast-feed consume 3.1 liters (about
13 cups) of fluids a day.
Beyond the tap: Many sources of water
You don't need to sip from your water bottle all day to satisfy
your fluid needs. Your diet, including the beverages you drink,
can provide a large portion of what you need. In an average adult
diet, food provides about 20 percent of total water intake. The
remaining 80 percent comes from beverages of all kinds.
Fruits and vegetables - besides being good sources of vitamins,
minerals and fiber - contain lots of water. For example, oranges
are 87 percent water, and cucumbers are 95 percent water. Milk,
juice and other beverages also have large amounts of water. Conversely,
dried fruits, nuts, grain products and baked goods generally contain
Make it count: Meet your water needs through food and beverages
Alcohol - such as beer and wine - and caffeinated beverages - such
as coffee, tea or soda - can contribute to your total fluid intake.
But your best beverage is still water. Water is calorie-free, inexpensive
when drawn from a faucet or fountain, and readily available in and
out of your home.
Thirst not always a reliable gauge
If you're healthy and not in any dehydrating conditions, you can
generally use your thirst as an indicator of when to drink water.
But thirst isn't always an adequate gauge of your body's need for
fluid replenishment. The older you are, the less you're able to
sense that you're thirsty. And during vigorous exercise, an important
amount of your fluid reserves may be lost before you feel thirsty.
So make sure that you're sufficiently hydrated before, during and
Increased thirst and increased urination, both in volume and frequency,
can be signs and symptoms of diabetes. With diabetes, excess blood
sugar (glucose) in your body draws water from your tissues, making
you feel dehydrated. To quench your thirst, you drink a lot of water
and other beverages and that leads to more frequent urination. If
you notice unexplained increases in your thirst and urination, see
your doctor. It may not necessarily mean you have diabetes. It could
be something else. And some people consume large amounts of water
and experience increased urine output not associated with any underlying
Diabetes - Staying safely hydrated
Make a conscious effort to keep yourself hydrated and make water
your beverage of choice. Nearly every healthy adult can consider
- Drink a glass of water with each meal and between each meal.
- Take water breaks instead of coffee or tea breaks.
- Substitute sparkling water for alcoholic drinks at social gatherings.
If you drink water from a bottle, thoroughly clean or replace the
bottle often. Every time you drink, bacteria from your mouth contaminate
water in the bottle. If you use a bottle repeatedly, make sure that
the bottle is designed for reuse. To keep it clean, wash your container
in hot, soapy water or run it through a dishwasher before refilling
Though uncommon, it's possible to drink too much water. Drinking
excessive amounts can overwhelm your kidneys' ability to get rid
of the water. This can lead to hyponatremia, a condition in which
excess water intake dilutes the normal amount of sodium in the blood.
People who are older, who have certain medical conditions such as
congestive heart failure and cirrhosis, or who are taking certain
diuretics are at higher risk of hyponatremia.