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

Many of us try to hack our way to better hydration, whether that means carrying a reusable water bottle, tracking our fluid intake or infusing our H2O with some fruit. But even if you know you should be staying hydrated, you might still be wondering, "How much water should I drink a day, exactly?"

Although there's no one equation for proper hydration (as it varies from person to person), there are some guidelines you can consider as you gauge the amount of water to drink daily.

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. In fact, you lose water every day through breath, sweat, urine and bowel movements.

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, the average adult should get anywhere from 11.5 cups to 15.5 cups of water per day, from drinking and water-rich foods.

(Note: Although this is an older recommendation, it's still widely regarded as a good guideline.)

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 use the following water intake calculator to find just how much water you need to function per your body weight, according to the University of Missouri System:

For example, if you weigh 180 pounds, you should aim for a minimum of 11.25 cups of water each day.

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, activity and if you live in hot/humid weather or at high altitudes, per the Mayo Clinic.

For example, older adults may need to be more aware of their water intake, as thirst levels can decrease as you get older, per the Cleveland Clinic.

Signs you're not drinking enough water include the following, per the Mayo Clinic:

• Thirst
• Dark-colored urine
• Peeing less frequently
• Feeling tired
• Dizziness
• Confusion

You may also notice constipation and dry skin if you're dehydrated over longer periods.

Like adults, children need water to function their best. But how much water does a child need? Here's how the daily hydration recommendations for children breaks down by age, per the Centers for Disease Control and Prevention (CDC) and American Academy of Pediatrics (AAP):

• ‌Younger than 6 months:‌ No additional water needed (these babies should only drink breast milk or formula)
• ‌Babies ages 6 to 12 months:‌ 4 to 8 ounces of water per day (in addition to breast milk or formula)
• ‌Toddlers ages 12 to 24 months:‌ 1 to 4 cups (8 to 32 ounces) of water per day
• ‌Children ages 2 to 5:‌ 1 to 5 cups (8 to 40 ounces) of water per day

Plain water and milk are the best drink choices for children, per the AAP. Kids older than 1 should meet their hydration needs from a combination of plain water and cow's milk.

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.

A good way to help ensure children ages 1 and older are 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.

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

The amount of water you should drink daily will depend on your body size but will also vary based on these factors:

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 daily or even several times per week, 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.

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.

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 before, during and after exercise to stay hydrated, according to ACE:

• ‌Before exercise:‌ 17 to 20 oz of water at least 2 hours prior to exercise
• ‌During exercise:‌ 7 to 10 oz. of water for every 10 to 20 minutes of exercise
• ‌After exercise:‌ 16 to 24 oz of water for each pound lost due to sweating

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.

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.

If you live in a warm climate or at a high altitude, make sure you're meeting your minimum hydration requirement (body weight in pounds divided by two equals the minimum ounces to drink) and look for signs of dehydration to make sure you're getting enough.

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.

People who are pregnant or chestfeeding may need to bump up their water intake, per the Mayo Clinic.

Hydration is important for anyone, but especially when you are pregnant. It can help form amniotic fluid around the fetus and help nutrients circulate throughout the body, per the American College of Obstetricians and Gynecologists (ACOG).

ACOG recommends pregnant people aim to drink 8 to 12 cups (64 to 96 ounces) of water per day, and the Institute of Medicine recommends about 10 cups (80 ounces).

During lactation (chestfeeding), a person's water needs increase because their body uses water to make breast milk. The Institute of Medicine recommends lactating people get about 13 cups of water or other beverages each day.

• ‌Pregnancy:‌ 8 to 12 cups of water per day
• ‌Lactation:‌ About 13 cups of water per day

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, like bloating from water, talk to your doctor about how to treat it.

Water does a lot for your body besides quench your thirst. After all, your body contains around 60 percent water, per the U.S. Geological Survey.

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

• Rids your body of waste through frequent urination, bowel movements and sweating
• Helps control your body temperature
• Lubricates your joints
• Protects your tissue
  
• Aids digestion
• Helps prevent constipation
• Helps keep your blood pressure in check

While there have been general associations between increased water intake and weight loss, one doesn't necessarily result in the other. In other words, there's no direct relationship between drinking more water and weight loss.

Basically, drinking water cannot help you lose weight without making other changes to your nutrition and exercise.

However, if you're making changes like eating more nutritious foods and working out more, drinking water may come with some benefits that can help you toward your weight-loss goal, including:

• Water has zero calories, which makes it a better choice for weight loss than higher-calorie drinks like soda or juice
• In some cases, you might confuse thirst for hunger, which can lead to unnecessary snacking, according to the Polycystic Kidney Disease Foundation
  
• Water supports healthy digestion and a healthy metabolism, per the Mayo Clinic, so your body can more efficiently turn the calories you eat and drink into energy
• Drinking enough water keeps you hydrated during exercise, which helps you get the most out of your workouts

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

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

In some cases, adding some healthy water flavorings to your bottle of H2O 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.

Keep a full pitcher in your fridge or on your counter at all times, per the Mayo Clinic. And consider investing in a reusable water bottle you can carry with you wherever you go.

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.

Keep a little notepad or journal near your fridge or in your kitchen.

You can also download a water intake calculator or reminder app like the Daily Water Tracker Reminder that will help you monitor your cups and can send you reminders when it's time for another sip.

If you're still struggling to stay hydrated, you can swap a few cups of plain water throughout the day for other hydrating beverages, per the Mayo Clinic, such as:

• Milk
• Juice
• Herbal tea
• Coconut water
• Carbonated water
• Kombucha
• Soups
• Broth

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

If you are unsure about the amount of water you need based on your overall health, environment, weight and activity level, consult with your doctor or a registered dietitian, who may be able to point you in the right direction and offer tips.

If you are experiencing symptoms of chronic dehydration or over-hydration, call your doctor, who may suggest you visit your nearest emergency room if symptoms worsen.

You'll know you're drinking enough water if you rarely feel thirsty or your urine is colorless or light, pale yellow. If in doubt, you can also drink water with each meal and between meals; before, during and after exercise; and whenever you feel thirsty, per the Mayo Clinic.

Signs you are dehydrated include the following, per the U.K.'s National Health Service (NHS):

• Dark or strong-smelling urine
• Dry mouth
• Thirst
• Headaches
• Less frequent urination
• Muscle cramps

While there may be times where you're incredibly thirsty and need to chug water, drinking water gradually throughout the day is more ideal. Too much water at once can increase the risk of hyponatremia, per the Mayo Clinic.

This is why it's important to keep a water bottle or cup handy throughout the day and take sips to help you stay hydrated, instead of chugging it all at once.

For most people, drinking a gallon of water a day is not harmful. A gallon is 128 ounces, or about 16 cups, which is just slightly over the high end of the daily recommendation for adults, according to the U.S. National Academies of Sciences, Engineering, and Medicine.

But if you have underlying conditions like congestive heart failure or end-stage kidney disease, it could be dangerous to drink a gallon of water, because your body is already holding onto so many fluids. Your body can't process all that extra water correctly, per the Cleveland Clinic.

That said, what about a half gallon? Is 64 ounces of water a day enough? This amount may be right for some people, but it will vary depending on your health, body size, physical activity and other factors.

No, water can't penetrate your skin enough to rehydrate you, per West Texas A&M University. It's better to stick to drinking water and eating hydrating foods.

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