How Much Water Should You Drink Every Day?

You’ve likely heard that it’s important to drink water, since water is crucial to the survival of living beings. But do you need to drink 8 glasses of water a day, as is often recommended? And what are the actual benefits of drinking water?

Below, we’ll separate fact from fiction when it comes to how much water you need. And we’ll cover how to tell whether you’re getting enough water.

How much water should you drink a day?

There isn’t one recommended water intake guideline that applies to all people. How much water to drink daily varies from person to person. But the Institute of Medicine of the National Academies states that people who are well-hydrated typically drink around:

• 3.7 L (125 oz) of water daily if they’re men

• 2.7 L (91 oz) of water daily if they’re women 

However, some people may need to drink more water than others. This depends on several factors:

• Weight: Individuals with larger bodies may require more fluid, since water makes up over two-thirds of an adult body’s weight. If you’re looking for a rough calculation of your own water needs, take your weight in pounds and divide that number in half. This is approximately how many ounces of water you should drink each day. So, a person who weighs 200 lbs should drink about 100 oz (or 3 L) of water per day.

• Environment and temperature: If you live in a tropical or hot area, you might need to drink more water to replace fluids lost through sweat. You may also need to drink more water during hotter months of the year. 

• Activity level: Your body will lose water with any amount of exercise, even if you don’t feel like you’re sweating a lot. So, if you’re physically active, you’ll need to increase your fluid intake to stay hydrated. This is especially true if you’re working out in hot weather or high altitudes. 

• Health: Some health conditions can increase your fluid loss. Common examples include high blood sugar, fever, urinary tract infections, and intestinal conditions that cause vomiting or diarrhea. If you have one of these health conditions, you may need to drink more water to stay hydrated. 

For most people, their normal drinking and eating patterns help them meet their body’s water needs. This means if you drink fluids when you get thirsty, you’re probably getting enough water. Unless your primary care provider tells you otherwise, you most likely don’t need to closely monitor your water intake.

Do you really need to drink 8 glasses of water a day?

No, there’s no evidence to support the common belief that the average adult should drink 8 glasses of water a day. Research has found that most people naturally get enough water when they let thirst be their guide. And, remember, you get hydration not only from beverages but from the foods you eat, too.

How much water should kids drink?

Kids need to drink between 4 to 8 cups of liquid beverages a day, depending on their age. Keep in mind that children also get hydration from other drinks — such as milk — in addition to water. 

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Here’s a general guide to how much your child should drink:

• Kids ages 1 to 3 need about 4 cups of liquid per day. 

• Kids ages 4 to 8 need about 5 cups of liquid per day.

• Kids over 8 years old need 7 to 8 cups of liquid each day.

Active children may need more water and hydration than this. Let your child drink when they’re thirsty. And make sure they have water or post-workout drinks available while playing sports or being active.

Is water the only way you can stay hydrated?

No, you get hydration from more than just water alone. All drinks contain water, including:

• Milk

• Tea

• Coffee

• Juice

• Electrolyte drinks
  

For most people, drinking these beverages along with plain water makes up 70% to 80% of their total fluid intake. The other 20% to 30% of most people’s total fluid intake comes from food. Fruits with high water content include tomatoes, watermelon, and pineapple. Vegetables with high water content include cucumbers, certain lettuces, and celery.

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Quiz: What foods are good for hydration?

What are the benefits of drinking water?

The human body is approximately 60% water. Your body depends on water to function properly. In fact, you couldn’t live for more than a few days without it. Water helps your body by:

• Transporting nutrients to organs via your blood

• Regulating your temperature

• Keeping your mouth clean

• Lubricating your joints and protecting sensitive tissues

• Removing harmful wastes through urine, sweat, and poop

• Helping blood flow easily through your veins

How to tell if your body is getting enough water

For most people, an easy way to figure out whether you’re getting enough water is to look at the color of your urine. Typically, urine should be a clear or pale-yellow color. If your urine appears dark yellow or amber, it may be a sign you need to drink more water. 

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Not drinking enough water can lead to dehydration, which is when the body doesn’t have enough water to carry out its normal functions. Usually, you can manage mild-to-moderate dehydration by just drinking more water. But the best choice for rehydrating depends on what’s causing the dehydration.

Signs you’re not getting enough water

When you have mild-to-moderate dehydration and need to drink more water, your body will likely send you some signs that include:

• Dark or strong-smelling urine

• Dry mouth 

• Thirst

• Headaches 

• Less frequent urination 

• Weakness and fatigue 

It’s important to note that this isn’t true for everyone. For example, someone with diabetes and high blood sugar might have clear urine but also be dehydrated. And someone with kidney disease might have darker urine, but be well hydrated. So, the above signs apply more to people who don’t have chronic medical conditions.

Reasons you might not get enough water to stay hydrated
Occasionally, you may be in a situation where you aren’t able to drink or retain enough water to rehydrate yourself adequately. Usually, this is because you can’t drink or eat enough to meet your body’s needs. 

For example, you may have an underlying medical condition that makes it difficult to get enough water. This includes conditions that affect your ability to experience thirst (like dementia) or your ability to swallow (like a stroke). It could also be because you simply don’t have an appetite. 

It’s also possible to lose more water than you can replace through drinking. This can happen if you have a serious infection with a high fever, vomiting, or diarrhea that won’t stop. It can also happen if you have a medical condition or take a medication that makes you urinate a lot. 

Depending on the situation, your healthcare provider may recommend oral replacement solutions, or you may need to have fluids replaced through an infusion into your vein. Rehydration solutions replace not only water, but also essential electrolytes, such as sodium and potassium.

How much water is too much?

Although rare, it’s possible to drink too much water. Overhydration can lead to a condition called hyponatremia. This is when the body doesn’t have enough sodium — an important electrolyte for fluid regulation. As a result, fluid causes the cells in the body to swell, including cells in the brain. 

This condition can lead to dangerous symptoms, including:

• Changes to your mental state, such as confusion or irritability

• Fatigue 

• Headaches

• Nausea and vomiting

• Muscle cramps or weakness

• Seizures

• Coma 

Typically, overhydration occurs with:

• Athletes who attempt to prevent dehydration by drinking too much water during strenuous activity 

• People who have health conditions — such as heart failure or kidney disease — that cause their bodies to hold onto water 

• People with underlying medical conditions that cause excessive thirst, which leads them to consume unusually large amounts of water

But, even in the absence of these conditions, a healthy individual who drinks too much water in a short period of time can develop hyponatremia. 

So, how much water is too much? There’s no specific amount of water that’s too much. But, if you find yourself drinking a gallon of water per day or more, it’s a good idea to speak with your healthcare provider. You can work together to figure out the right amount of fluid you should be drinking daily to stay hydrated.

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Written by:

Kara-Marie Hall, RN, BSN, CCRN

Kara-Marie Hall, RN, BSN, CCRN, is a registered nurse who specializes in writing health content that connects with everyone — no matter where they are in their health journey. She has over 10 years of clinical experience in a variety of specialties, including critical care, surgery, and hospice.

Edited by:

Meredith Hoffa

Meredith Hoffa is a senior health editor at GoodRx, where she leads journalists and clinicians covering various well-being topics, particularly in diet and nutrition.

Reviewed by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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