You may have heard that you should aim to drink eight 8-ounce glasses of water per day. How much you should actually drink is more individualized than you might think.
The Institute of Medicine (IOM) recommends that men drink at least 101 ounces of water per day, which is a little under 13 cups. They say women should drink at least 74 ounces, which is a little over 9 cups.
Still, the answer to exactly how much water you should drink isn’t so simple.
While the eight glasses rule is a good start, it isn’t based on solid, well-researched information.
Your body weight is made up of 60 percent water. Every system in your body needs water to function. Your recommended intake is based on factors including your sex, age, activity level, and others, such as if you’re pregnant or breastfeeding.
The current Institute of Medicine (IOM) recommends for people ages 19 and older is around 131 ounces for men and 95 ounces for women. This refers to your overall fluid intake per day, including anything you eat or drink that contains water, like fruits or vegetables.
Of this total, men should get around 13 cups from beverages. For women, it’s 9 cups.
Recommendations for kids have a lot to do with age.
Girls and boys between 4 and 8 years old should drink 40 ounces per day, or 5 cups.
This amount increases to 56–64 ounces, or 7–8 cups, by ages 9 to 13 years.
For ages 14 to 18, the recommended water intake is 64–88 ounces, or 8–11 cups.
Women of reproductive age
If you’re pregnant or breastfeeding, your recommendations change.
Breastfeeding women may need to up their total water intake to 104 ounces, or 13 cups.
|Demographic||Daily recommended amount of water (from drinks)|
|children 4–8 years old||5 cups, or 40 total ounces|
|children 9–13 years old||7–8 cups, or 56–64 total ounces|
|children 14–18 years old||8–11 cups, or 64–88 total ounces|
|men, 19 years and older||13 cups, or 104 total ounces|
|women, 19 years and older||9 cups, or 72 total ounces|
|pregnant women||10 cups, or 80 total ounces|
|breastfeeding women||13 cups, or 104 total ounces|
You may also need to drink more water if you live in a hot climate, exercise often, or have a fever, diarrhea, or vomiting.
Add an additional 1.5 to 2.5 cups of water each day if you exercise. You may need to add even more if you work out for longer than an hour.
You may need more water if you live in a hot climate.
If you live at an elevation greater than 8,200 feet above sea level, you may also need to drink more.
When you have a fever, vomiting, or diarrhea, your body loses more fluids than usual, so drink more water. Your doctor may even suggest taking drinks with electrolytes to keep your electrolyte balance more stable.
Water is important for most processes your body goes through in a day. When you drink water, you replenish your stores. Without enough water, your body and its organs can’t function properly.
Benefits of drinking water include:
- keeping your body temperature within a normal range
- lubricating and cushioning your joints
- protecting your spine and other tissues
- helping you eliminate waste through urine, sweat, and bowel movements
Drinking enough water can also help you look your best. For example, water keeps your skin looking healthy. Skin is your body’s largest organ. When you drink plenty of water, you keep it healthy and hydrated.
And because water contains zero calories, water can be an excellent tool for managing your weight, as well.
There are risks of drinking too little or too much water.
Your body is constantly using and losing fluids through actions like sweating and urinating. Dehydration happens when your body loses more water or fluid than it takes in.
Symptoms of dehydration can range from being extremely thirsty to feeling fatigued. You may also notice you aren’t urinating as frequently or that your urine is dark.
In children, dehydration may cause a dry mouth and tongue, lack of tears while crying, and fewer wet diapers than usual.
Dehydration may lead to:
- confusion or unclear thinking
- mood changes
- kidney stone formation
Mild dehydration may be treated by drinking more water and other fluids.
If you have severe dehydration, you may need treatment at the hospital. Your doctor will likely give you intravenous (IV) fluids and salts until your symptoms go away.
Drinking too much water may be dangerous to your health as well.
When you drink too much, the extra water can dilute the electrolytes in your blood. Your sodium levels decrease and can lead to what is called hypothermia.
- nausea or vomiting
- muscle spasms, cramps and weakness
Water intoxication hyponatremia is uncommon. People with a smaller build and children are at a higher risk of developing this condition. So are active people, like marathon runners, who drink large quantities of water in a short period of time.
If you’re at risk due to drinking large quantities of water for exercise, consider drinking a sports drink that contains sodium and other electrolytes to help replenish the electrolytes you lose through sweating.