How Much Water Should You Drink?
The answer depends on your health, activity level and local weather
The standard advice is to aim for eight 8-ounce glasses of water a day. Yet, no body of evidence exists to support the 8-cup rule. Drinking five or six 8-ounce glasses a day may be adequate for some people—though there are plenty of exceptions. More water is required during hot weather, high humidity, high altitudes or vigorous exercise. People with health conditions such as fever, vomiting, diarrhea, bladder infections or kidney stones may also need to drink more water. So do women who are pregnant or breastfeeding. Talking with your health care provider can help you decide what’s optimal for you.
Despite the controversy, the following facts still hold water: We lose fluids in our urine, sweat and feces on average at a rate of about 11.5 cups per day for women, or 15.5 cups for men. People on the standard American diet (containing 2.7 servings per day of fruits and vegetables combined) replenish only about 20 percent of their fluid needs from food, according to the National Academies of Sciences. By necessity, the remaining 80 percent must come from drinking liquids.1 This means the average woman on the standard American diet must drink 9 daily cups of liquids, and the average man 12 cups. Almost any beverage can help improve hydration, but the best source is plain water.
Health benefits of water
Your body needs water to function properly. Water helps maintain your body temperature, maintains kidney function, lubricates and cushions your joints and protects the tissues of your body, which are composed by weight of 50 to 70 percent water. In addition, you need water to eliminate your body’s waste products through your urine, perspiration and bowel movements.
In contrast, inadequate water intake can lead to dehydration. Common symptoms of the condition include a lack of energy or fatigue as well as headaches, muscle cramps or dizziness. In hot weather, heat exhaustion and heat stroke are added risks. Chronic dehydration can disrupt normal physiology and lead to cellular stress, both of which can accelerate aging.2
Other hydration options
Many types of beverages besides water can provide hydration. Seltzer, milk, juice, coffee and tea are good options for improving fluid intake. Caffeinated beverages have a diuretic effect, increasing urination and decreasing the absorption of water; this effect is mild when caffeine is consumed in moderation. Alcoholic beverages have a strong diuretic action that can quickly lead to dehydration if you don’t drink enough water. Soda, energy or sports drinks and other sugary drinks may aid hydration but contain empty calories that often add to weight gain.
Many fruits and vegetables are excellent sources of water. Some of the best ones for improving hydration include melons, peaches, plums, cucumbers, zucchini and tomatoes. A small wedge of watermelon, for example, contains 7 ounces of water. Other foods such as soups, smoothies and yogurt are also good fluid sources.
No matter if you drink water or other beverages or eat water-rich foods, all of these sources count toward the 9 cups of daily fluids the average woman needs on the standard American diet, or 12 cups for the average man.
Staying hydrated, simplified
There’s a much simpler way to determine your hydration status. Keep an eye on your urine and how you feel. Thirst is usually a good indication it’s time to drink. As we grow older, however, many people don’t feel thirsty even when they’re dehydrated. Symptoms like fatigue, headache, cramps or dizziness may also indicate low-fluid status. Another method is to monitor your weight. A weight drop after heavy exercise or sweating may indicate water loss. To find out how much water you’ve lost, substract your weight afterwards from your weight beforehand. You can replenish your fluids by drinking 16 ounces of liquids for every pound you lost.
Another excellent hydration guide is to inspect your urine. As a general rule, aim for urine that looks colorless or light yellow. Dark urine may be a sign of underhydration. Tip: Medications can affect the color of your urine; riboflavin and other B vitamins make it more yellow and pyridium turns it orange.
How can you stay hydrated for optimal health? Drink fluids with meals as well as in between. And drink before, during and after exercise. To flavor your water if desired, you can add citrus slices, muddled fruit, a splash of juice, 100 percent fruit juice ice cubes or—for even more variety—cucumber slices and fresh mint. Mugs up for water!
This newsletter is for educational purposes only. It is not intended as a substitute for medical advice or treatment; before adhering to any recommendations in this newsletter consult your healthcare provider.
Report Sets Dietary Intake Levels for Water, Salt, and Potassium To Maintain Health and Reduce Chronic Disease Risk. National Academies of Sciences, Engineering and Medicine, 2/11/2004. www.nationalacademies.org
Water: How much should you drink every day? Mayo Clinic, 10/12/2022. www.mayoclinic.org
If one is engaged in a very sweaty activity, waiting until you feel thirsty is too late. One needs to drink before they feel thirsty or their performance will be impacted before they catch up on their water requirements.