Water is essential for keeping your body working normally. It helps regulate body temperature and removes waste. Every day, your body loses about two quarts of water when you exhale, sweat, and urinate. You replace most of this by eating and drinking fluids. Physical activity and extreme heat and humidity in the summer months can cause you to lose even more water. If you lose more water than you take in, you can become dehydrated.

Who’s at Risk for Dehydration

Dehydration is a serious health risk. It’s most often associated with heat waves, but dehydration can happen any time of year if you have an illness that includes diarrhea, vomiting, fever, or sweating. Medications that increase urination, including some antihistamines and blood pressure medications, can also dehydrate you. People with chronic illnesses that affect kidney function, such as diabetes, and the elderly are at high risk for dehydration. As we age, our bodies do not hold on to water or adapt to extreme heat and humidity as well as they once did.

Warning Signs of Dehydration

You may not always feel thirsty when you are dehydrated. For example, the sense of thirst diminishes with age, so by the time you feel thirsty you may have lost too much fluid.

Rather than go by thirst, color of urine is a better indicator of how hydrated your body is. It should be clear or light yellow. Dark or amber-colored urine is a sign of severe dehydration. Other signs of severe dehydration include:

• Little or no urine
• Dry skin (it stays folded when pinched)
• Irritability, dizziness, or confusion

Preventing Dehydration

Not getting enough fluids, especially if you are physically active or it is hot outside, is the most obvious cause of dehydration, but it isn’t the only one. It’s important to stay hydrated all year long:

• During the winter, indoor air can lead to dry skin and dry mucous membranes, so your need for fluids increases. In addition, you may need to replace sweat lost while wearing heavy clothing.
• At the first sign of illness, including a cold, increase your water intake. If dehydration is caused by diarrhea, avoid fruit juice, sodas, and caffeinated beverages.
• When it’s hot or humid outside, additional water helps to keep your body cool and hydrated.

Eat and Drink to Stay Hydrated

For most of us, drinking plenty of fluids and eating foods with a high water content—including most fruits and vegetables—can keep our bodies properly hydrated. Here are more tips for staying hydrated:

• Drink 6 to 8 glasses of fluid every day. (This amount includes the water in foods and beverages.)
• Water is the best fluid for hydration because it has no calories, sugar, carbonation, or preservatives.
• Limit fruit juices, sodas, and fitness waters as they contain sugars that can make you feel thirstier.
• Eat fruits and vegetables that are high in water, such as grapes, oranges, cantaloupe, honeydew, watermelon, apples, tomatoes, lettuce, cucumber and celery. (See the table below for other choices.)
• Avoid or limit coffee, tea, alcohol, and soda containing caffeine—these increase urination, causing you to lose water at a faster than normal rate.

Make Hydration a Part of Your Daily Routine

• Have a glass of water when you wake up in the morning.
• Keep a glass of water next to your bed at night.
• Carry a water bottle with you if you are away from home for long periods of time.
• Avoid the mid-day sun and limit physical activity when it is very hot outside.
• Schedule outdoor activities in the morning or evening.

How Much Water Do You Need?

Most adults need about two quarts of fluids every day, but that amount increases with heat and humidity, and can be affected by activity level, medications, and other factors. Before you guzzle a half-gallon of water, remember that most fluids count toward that 64 ounces, and many foods do, too. Raw fruits and vegetables are particularly high in water.

These Foods Boost Hydration

This table gives the percentage of water in some foods, and how much of each you need to eat to obtain about ½ cup, or 4 ounces, of water:

By drinking enough fluid every day and knowing the symptoms of dehydration, you can help your body stay healthy.