Do You Really Need to Drink 8 Glasses of Water a Day?

Your body needs plenty of water to function properly, so you'll typically want to hydrate with more than eight glasses throughout the day.
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Stay Hydrated, My Friends takes a look at all things hydration, dehydration and the different ways to meet your daily water needs.

We're all looking to hack our way to better hydration, whether that means carrying a huge water bottle, tracking our fluid intake or infusing our H2O with some fruit. Nevertheless, you still may not be drinking enough water for your daily needs — so, how much water should you drink a day?

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Although there's no one equation or rule to proper hydration (as it varies from person to person), there are some guidelines you can consider as you gauge how much water to drink per day.

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Need a way to easily track your daily water intake? Download the MyPlate app to do the job, so you can stay focused and achieve your goals!

How Much Water Should Adults Drink a Day?

Good hydration is crucial for your health because every part of your body needs water in order to function properly, according to the Mayo Clinic. However, it turns out that the classic recommendation of 8 cups of water per day doesn't apply to everyone.

According to the U.S. National Academies of Sciences, Engineering, and Medicine, here's about how much the average adult should drink per day (although this is an older recommendation, it's still widely regarded as a good guideline):

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  • People assigned female at birth:​ 2.7 liters (about 11.5 cups)
  • People assigned male at birth:​ 3.7 liters (about 15.5 cups)

While this may seem like a lot of water to guzzle on the daily, keep in mind that about 20 percent of your daily recommended fluids will probably come from other foods and drinks.

You can also try the following equation to calculate how much water you need to function per your body weight, according to the University of Missouri System. Although this is a general hydration guideline, the exact amount of water you should drink each day will vary from person to person and day to day, depending on factors like overall health, diet and activity, per the Mayo Clinic.

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How to Calculate How Many Ounces of Water You Should Drink a Day

Body weight (in pounds) ​÷​ 2 = minimum ounces of water you should drink per day.

If you're looking for a quick conversion, 8 ounces of water means 1 cup of water.

How Much Water Should Babies Drink a Day?

Like adults, children need water to function their best. But their daily hydration recommendations are different: For instance, how much water a 1-year-old needs to drink will differ from an adult. In general, children ages 6 to 12 months can have 4 to 6 ounces of water to drink per day (in addition to their usual breast milk or formula), per the Centers for Disease Control and Prevention (CDC).

Your child may need more or less water depending on their size, climate and whether or not they're sick. Talk to your pediatrician to determine precisely how much water your 1-year-old (or children of other ages) needs.

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Per the National Health Service, you should also visit your doctor if your child shows signs of dehydration, including:

  • Infrequent urination or dark yellow pee
  • Dizziness
  • Excessive sleepiness
  • Sunken eyes
  • No tears when they cry
  • Dry mouth
  • Cold or splotchy hands or feet
  • A soft spot on their head that sinks in

A good way to help ensure your child is meeting their daily fluid requirements is to offer milk with their meals and water in between, says pediatrician Jennifer Shu, MD. A 1-year-old may not be able to tell you how much water they need or when they're thirsty, so try offering them a small amount every hour they're awake. Serving it in a training cup or with a straw may also make them more receptive to drinking water if you're having difficulty.

Tip

Your child still needs the calories and nutrients they get from milk and solid foods, however, so make sure they're not only filling up on water, per the CDC.

3 Factors That Affect Your Water Intake

As mentioned, your daily required water or fluid intake will vary depending on these factors.

1. Physical Activity

First, look to your activity levels, according to the Mayo Clinic. When you sweat, your body loses fluids that you need to replenish. And when your fluid loss outweighs your intake, you can experience dehydration. Per the Mayo Clinic, symptoms of dehydration include:

  • Fatigue
  • Confusion
  • Extreme thirst
  • Infrequent urination
  • Mood changes like irritability

So, if you're an active person, it's important to drink plenty of water before, during and after exercising.

2. Your Environment

Where you reside is another element you should consider — especially if you live in warm temperatures.

Again, your levels of perspiration affect the amount of water you'll need to stay hydrated, so those living in warm, humid climates will probably need more fluids to replenish those lost from sweating, per the Mayo Clinic. The same goes for people living at a high elevation.

3. Illness

This is another factor you must consider in gauging your daily water needs, according to the Mayo Clinic.

For instance, if you're vomiting or sick with a fever, you'll probably be depleted of fluids and need to drink more. Doctors may advise people with certain bladder conditions to drink extra water, too.

So, how much water should you drink when you're sick? Though there's no one amount that works for everyone, you should drink more than your usual number of ounces per day to replenish fluids lost from symptoms like vomiting or diarrhea, per the Harvard T.H. Chan School of Public Health. In other words, drink enough to avoid dehydration, because remember — you can also feel sick from not drinking enough water.

Women who are pregnant or breastfeeding may also need to bump their water intake slightly, per the Mayo Clinic.

Why Are You Retaining So Much Water?

Diet, medications and underlying medical conditions can all cause your body to trap excess fluid in your tissues, which is a condition called edema. Per the Cleveland Clinic, you can tell if you're retaining water from edema if you have these symptoms:

  • Swollen, stretched or shiny skin in the affected area
  • Pressing on the swollen area leaves a dimple
  • Trouble walking if you have edema in your legs
  • Coughing or trouble breathing if you have edema in your lungs

If you're retaining water, talk to your doctor about how to proceed, as treatment may depend on the underlying cause of edema (which does not include simply drinking too much water). Potential reasons your body is retaining fluid include:

  • Heart, lung, liver or kidney disease
  • Thyroid disease
  • Allergic reactions
  • Too much salt in your diet
  • Weak valves in your leg veins
  • Pregnancy
  • Certain blood pressure and pain medications

Benefits of Hydration

Water does a lot for your body besides quench your thirst.

Here are the benefits of drinking water, according to Harvard Health Publishing:

  • It rids your body of waste through urination, bowel movements and sweating
  • It helps control your body temperature
  • It lubricates your joints
  • It protects your tissue
  • It aids digestion
  • It prevents constipation
  • It helps keep your blood pressure in check

Hydration and Exercise

Drink water about two hours before exercise to make sure you have enough fluids to keep you hydrated during and after your workout.
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In just one hour of exercise, your body can lose up to a quart of water, depending on your exercise intensity and the temperature, according to the American Council on Exercise (ACE).

So, if you're an active adult who exercises several times per week or even daily, you'll need a little more water than the recommended minimum to keep your body hydrated.

You'll also want to drink your fluids strategically when you're exercising to keep your body fueled, according to ACE. If you have an intense training session or other strenuous exercise like a soccer match or run planned, it's advised that you drink a little more fluids than usual in the 24 hours leading up to the activity.

But how do you properly hydrate for sports, exactly? While the precise amount varies based on your circumstances, this is about how much water a runner or other athlete should drink in one day to stay hydrated while training, according to the ACE:

  • Start to hydrate two hours before exercise with 17 to 20 ounces of fluid.
  • Every 10 to 20 minutes during exercise, drink 7 to 10 ounces of fluid.
  • For every pound of water weight lost during exercise, drink 16 to 24 ounces of fluid.

And if you're going on a summer hike, always bring more water than you think you'll need. According to a small June 2020 study in the ​International Journal of Environmental Research and Public Health,​ most hikers did not bring enough fluid with them on their hike to compensate for their sweat loss in the summer heat, which resulted in dehydration.

Although water is generally the best source of hydration, some people opt for sports drinks for energy and extra sodium to encourage more fluid retention.

Another perk of drinking enough during exercise? Being properly hydrated can help reduce the risk of injury by keeping your body functioning at its best and helping you avoid excessive strain, per the ACE.

Tip

By the time you feel thirsty, you're already on your way to dehydration, per the Cleveland Clinic. Accordingly, it's especially important to drink enough fluids when you're in the sun, on hot days and during strenuous activity to avoid dehydration.

Water and Weight Loss

While there have been general associations between increased water intake and weight loss, one doesn't necessarily result in the other. There's no conclusive evidence showing a relation between drinking more water and weight loss.

But water does help your body's absorption of nutrients and has the ability to promote regular digestion, according to the Mayo Clinic. That's because drinking water before and after a meal can help your body break down food more effectively.

In some cases, you can confuse thirst for hunger, which can lead to unnecessary snacking, according to the Polycystic Kidney Disease Foundation. While this doesn't apply to everyone, the tendency to eat when thirsty may indicate why some people lose weight when they drink more water.

How to Drink More Water

If you're rarely thirsty and notice your urine is clear or light yellow in color, that's a sign that you're probably drinking enough, according to the Mayo Clinic.

Although it's evident that drinking water is necessary for good health, some may struggle to guzzle down sufficient water each day. Luckily, there are a few tricks you can try to increase your hydration.

1. Try Other Fluids

In some cases, adding some flavor to your water may encourage you to drink more, per the Mayo Clinic. Try infusing your water with lemon juice, fruit or herbs. Fresh fruits or citrus can add some zest to your glass without tacking on added sugars. You can also fill your shopping cart with these healthy flavored waters.

Per the Mayo Clinic, you can also switch it up by hydrating with other fluids, including:

  • Milk
  • Juice
  • Herbal tea

And drinks aren't the only route to getting enough fluids — you can also munch on the following hydrating foods:

  • Lettuce
  • Celery
  • Bok choy
  • Cucumber
  • Tomates
  • Watermelon

Can You Absorb Water Through Your Skin?

While you can get your fluids through foods and drinks, water can't penetrate your skin enough to rehydrate you, per West Texas A&M University.

2. Make Your Water Readily Accessible

Keep a full pitcher in your fridge or on your counter at all times, per the Mayo Clinic. In some cases, people tend to just forget to drink water. But if it's always within eyesight, hydration will be less likely to slip your mind.

3. Keep Track of Your Fluid Intake

Keep a little notepad or journal near your fridge or in your kitchen. You can also download an app like MyPlate or the Daily Water Tracker Reminder that will help you monitor your cups and can send you reminders when it's time for another sip.

Can Too Much Water Make You Nauseous?

If water makes you feel sick, nauseous or you throw up from drinking too much, you may be dealing with overhydration, per University of Utah Health. This condition — called hyponatremia — can occur when too much water dilutes your electrolyte levels. Though it's rare, it's most common in cases of extreme endurance activities like marathon running.

Besides stomach upset, symptoms of hyponatremia include:

  • Headache
  • Confusion
  • Muscle weakness or cramping
  • In severe cases, coma or seizures

To avoid hyponatremia, don't force yourself to over-drink, and remember to replenish electrolytes during extreme exercise. If you're already showing symptoms of overhydration, talk to your doctor about how to treat it.

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