Daily Water Intake: Is Eight Glasses the Right Amount for You?

Most of us have heard that drinking eight glasses of water a day is an ideal amount and while it’s certainly a reasonable goal, it is not based on science. While some people can drink less and stay hydrated, others may need more, especially during the summer months when you’re spending more time outdoors in the warmer weather.

So how much fluid does the average, healthy adult living in a temperate climate need? The National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is about 11.5 cups (2.7 liters) of fluids a day for women and about 15.5 cups (3.7 liters) for men.

But, there are several factors that may cause you to need to adjust your total daily water intake, including: 

• Age. As you age, your body doesn’t adjust the rate of sweat loss as well, so drinking water even when you’re not thirsty is important.
• Environment. Hot or humid weather can make you sweat and requires additional fluid. Dehydration also can occur at high altitudes.
• Exercise and activity level. If you do any activity that makes you sweat, you need to drink extra water to cover the fluid loss. It’s important to drink water before, during and after a workout.
• Overall health. Your body loses fluids when you have a fever, vomiting or diarrhea. Drink more water or follow a doctor’s recommendation to drink oral rehydration solutions. Other conditions that might require increased fluid intake include bladder infections and urinary tract stones.
• Pregnancy and breastfeeding. During pregnancy, your body needs more water to adjust to the demands of your changing body, and to produce extra blood and amniotic fluid. Water is also a key component of breast milk and is essential for good lactation. Drinking enough water prevents dehydration which can lead to serious complications such as headaches, nausea, cramps, edema and dizziness. This is especially important in the third trimester when significant dehydration can cause contractions that can trigger preterm labor.

“There is no one-size-fits-all answer to how much water you need to drink per day since fluid needs vary among individuals," said BayCare’s VP/Chief Quality Officer Dr. Laura Arline, MD, FACP, FAAP. "Our age, activity level, health conditions, and outside temperatures all play a role in determining optimal fluid intake. Many of our foods and drinks naturally have water in them."

Water helps your body keep a normal temperature, lubricates and cushions joints, protects your spinal cord and other sensitive tissues, and gets rid of wastes through urination, perspiration and bowel movements. Adult humans are 60% water, and our blood is 90% water, making its consumption essential for the kidneys and other bodily functions. When you’re dehydrated, it can result in unclear thinking or mood changes, cause your body to overheat, and lead to constipation and kidney stones. 

Additionally, if you’re dieting, water intake aids in weight loss by increasing fat metabolism and decreasing cravings. Water has no calories, so it can also help with managing body weight and reducing calorie intake when substituted for drinks with calories, such as sweet tea or regular soda. A 2016 study by the Journal of Human Nutrition and Dietetics found that people who were steady water drinkers consumed less cholesterol, fat and salt as part of their daily diet resulting in overall weight loss compared to people who were dehydrated or didn’t drink enough water.

If you’re struggling to add more water to your daily beverage intake, the Centers for Disease Control and Prevention (CDC) recommends the following tips:

• Don’t wait until you’re thirsty to drink! Carry a reusable water bottle or insulated tumbler with you, refill it as needed and sip throughout the day.
• Think ahead. Freeze some water bottles and take one with you for ice-cold water all day long.
• Replace other drinks with water. Choose water over sugary drinks and opt for water when eating out to save money and reduce calories.
• Flavor your water. Add a wedge of lemon or lime, a slice of orange or a liquid water enhancer to your water to help improve the taste. Cucumber, watermelon, strawberries and herbs are also delicious options.
• Include high-water fruits and vegetables in your daily diet. According to the USDA, high-water fruits and vegetables are ones that are 89% or more water. Hydrating fruits include strawberries, grapefruit, cantaloupe and watermelon. Peaches, Asian pears, blackberries, papaya, nectarines, plums, oranges, apricots, pineapple, raspberries, apples, blueberries and mangos are all more than 80% water and are also good choices. High-water vegetables include lettuce, celery, Bok choy, radishes, cucumber, zucchini, watercress, tomatoes, green bell peppers, asparagus, portabella mushrooms, Swiss chard, okra, cabbage, cauliflower, broccoli and spinach.

No matter how you enjoy your water, it is vital to make sure you are consuming the right amount of it for your body and to adjust your intake based on your individual factors.

"It is actually possible to take in too much water if you have certain health conditions such as kidney, liver, or specific heart problems, or if you’re taking medications that make you retain water," added Arline."If you’re not sure the right amount of water or fluids to drink per day, check with your healthcare provider."

One of the best self-care activities you can do for your body and your mind is to drink water.