Tribune Print Share Text

How much water is enough?

Created date

July 23rd, 2013
A row of glasses of water

Water is important to every part of your body. Among other functions it clears vital organs of toxins; provides moisture for your ears, nose, throat, and joints; maintains your temperature; and carries nutrients to every cell in your body.

You lose water in a number of ways, including from breathing, sweating, urinating, and moving your bowels. When there isn’t enough water in your body, dehydration results and even a mild case can cause weakness and fatigue. Signs include urinating less often than usual and a dry mouth. Aging changes can make you more prone to dehydration. According to the American College of Sports Medicine, your body becomes less able to conserve water and your sensation of thirst decreases.

How much is enough?

Remember the rule to drink eight 8 oz. cups of water a day? “The 8 x 8 rule was established in the 1800s by the inventor of Kellogg’s cereals,” says Joel D. Posner, M.D., medical director at Riderwood, an Erickson Living community in Silver Spring, Md. “There have been a few studies that show an association between higher water consumption and a reduced incidence of heart disease, but there is little scientific evidence that there is a benefit to this specific amount.”

The Institute of Medicine currently recommends about 13 cups of total beverages a day for men and about 9 cups for women. “These recommendations were based on experts’ opinions, but few facts,” Posner says. “The amount of water you need is based on your weight, how active you are, your environment, the time of year, how healthy you are, and the medications you’re taking. It also depends on the amount of salt in your diet.”

In addition, people who live at altitudes over 8,200 feet may urinate more and breathe rapidly so their needs may be greater. If you have fever, vomiting, or diarrhea, you may also need more water than usual.

“In general, people with health conditions that affect the fluid balance in their bodies need to pay particular attention to how much fluid they get every day,” Posner adds. “Anyone with medical conditions should consult their doctor about their specific needs.”

“Overall, if you measure throughout the day and put out a little over six cups of diluted urine, you’re probably well enough hydrated,” Posner says.

What to drink

“Only 80% of the fluid you get comes from what you drink,” Posner explains. “The other 20% comes from food. Tomatoes, for example, are 90% water.” Other foods high in water are melons, celery, and citrus fruits.

You don’t have to drink water alone. Caffeine, sugar-sweetened drinks, and alcohol all count, although they should not be the main source of your daily intake. “Caffeine is a mild diuretic, but it doesn’t get more powerful the more you drink,” Posner says. “But you have to keep that in mind if you are on prescription diuretics. Alcohol is an even stronger diuretic than caffeine.”

Avoiding too many bathroom breaks

You may be hesitant to drink more because you feel like you’ll spend all day (or night) in the bathroom. This can happen for a number of reasons. “There’s a hormone in younger people that suppresses the formation of urine during the night,” Posner says. “Older people have less of this hormone or none at all.”

Reducing the amount of liquid a few hours before bedtime may help, but there is a confounding element to that strategy. “Limiting what you drink concentrates the urine, which makes it more irritating to the bladder and increases the urge to urinate,” Posner says. “As you age, your bladder gets stimulated easily.

“There’s no easy answer or single formula for everyone,” Posner continues. “Learn more about your body’s specific needs by talking to your doctor.”