How much water should you drink each day?
- How much water should you drink each day? A simple question
with no easy answers. Studies have produced varying recommendations
over the years, but in truth, your water needs depend on many
factors, including your health, how active you are and where you
live.Though no single formula fits everyone, knowing more about
your body's need for fluids will help you estimate how much water
to drink each day. Health benefits of water: Water is your body's
principal chemical component, making up, on average, 60 percent of
your body weight. Every system in your body depends on water. For
example, water flushes toxins out of vital organs, carries
nutrients to your cells and provides a moist environment for ear,
nose and throat tissues. Lack of water can lead to dehydration, a
condition that occurs when you don't have enough water in your body
to carry out normal functions. Even mild dehydration can drain your
energy and make you tired.
- Every day you lose water through your breath, perspiration,
urine and bowel movements. For your body to function properly, you
must replenish its water supply by consuming beverages and foods
that contain water.Several approaches attempt to approximate water
needs for the average, healthy adult living in a temperate climate.
Replacement approach. The average urine output for adults is about
1.5 liters (6.3 cups) 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 total fluid intake, so
if you consume 2 liters of water or other beverages a day (a little
more than 8 cups) along with your normal diet, you will typically
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 the 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 advises that men
consume roughly 3 liters (about 13 cups) of total beverages a day
and women consume 2.2 liters (about 9 cups) of total beverages a
day.Even apart from the above approaches, if you drink enough fluid
so that you rarely feel thirsty and produce 1.5 liters (6.3 cups)
or more of colorless or slightly yellow urine a day, your fluid
intake is probably adequate. Factors that influence water needs:
You may need to modify your total fluid intake depending on how
active you are, the climate you live in, 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 need to drink
extra water to compensate for the fluid loss. An extra 400 to 600
milliliters (about 1.5 to 2.5 cups) of water should suffice for
short bouts of exercise, but intense exercise lasting more than an
hour (for example, running a marathon) requires more fluid intake.
How much additional fluid you need depends on how much you sweat
during exercise, the duration of your exercise and the type of
activity you're engaged in. During long bouts of intense exercise,
it's best to use a sports drink that contains sodium, as this will
help replace sodium lost in sweat and reduce the chances of
developing hyponatremia, which can be life-threatening. Also,
continue to replace fluids after you're finished exercising.
Environment. Hot or humid weather can make you sweat and requires
additional intake of fluid. Heated indoor air also can cause your
skin to lose moisture during wintertime. Further, altitudes greater
than 8,200 feet (2,500 meters) may trigger increased urination and
more rapid breathing, which use up more of your fluid reserves.
Illnesses or health conditions. Signs of illnesses, such as fever,
vomiting and diarrhea, cause your body to lose additional fluids.
In these cases you should drink more water and may even need oral
rehydration solutions, such as Gatorade, Powerade or CeraLyte.
Also, you may need increased fluid intake if you develop certain
conditions, including bladder infections or urinary tract stones.
On the other hand, some conditions such as heart failure and some
types of kidney, liver and adrenal diseases may impair excretion of
water and even require that you limit your fluid intake. Pregnancy
or breast-feeding. Women who are expecting or breast-feeding need
additional fluids to stay hydrated. Large amounts of fluid are used
especially when nursing. The Institute of Medicine recommends that
pregnant women drink 2.3 liters (about 10 cups) of fluids daily and
women who breast-feed consume 3.1 liters (about 13 cups) of fluids
- Although it's a great idea to keep water within reach at all
times, you don't need to rely only on what you drink to satisfy
your fluid needs. What you eat also provides a significant portion
of your fluid needs. On average, food provides about 20 percent of
total water intake, while the remaining 80 percent comes from water
and beverages of all kinds. For example: many fruits and
vegetables, such as watermelon and tomatoes, are 90 percent to 100
percent water by weight. Beverages such as milk and juice also are
composed mostly of water. Even beer, wine and caffeinated beverages
--- such as coffee, tea or soda --- can contribute, but these
should not be a major portion of your daily total fluid intake.
Water is one of your best bets because it's calorie-free,
inexpensive and readily available.
- It's generally not a good idea to use thirst alone as a guide
for when to drink. By the time you become thirsty, it's possible to
already be slightly dehydrated. Further, be aware that as you get
older your body is less able to sense dehydration and send your
brain signals of thirst. Excessive thirst and increased urination
can be signs of a more serious medical condition. Talk to your
doctor if you experience either.To ward off dehydration and make
sure your body has the fluids it needs, make water your beverage of
choice. Nearly every healthy adult can consider the following:
Drink a glass of water with each meal and between each meal.
Hydrate before, during and after exercise. Substitute sparkling
water for alcoholic drinks at social gatherings. If you drink water
from a bottle, thoroughly clean or replace the bottle often.Though
uncommon, it is possible to drink too much water. When your kidneys
are unable to excrete the excess water, the electrolyte (mineral)
content of the blood is diluted, resulting in low sodium levels in
the blood, a condition called hyponatremia. Endurance athletes,
such as marathon runners, who drink large amounts of water are at
higher risk of hyponatremia. In general, though, drinking too much
water is rare in healthy adults who consume an average American
diet. If you're concerned about your fluid intake, check with your
doctor or a registered dietitian. He or she can help you determine
the amount of water that's best for you.