How much water can you safely drink in a day

What Factors Affect Fluid Needs?

Various factors can increase or decrease the amount of fluid your body needs to function at its best.

Birth Sex

Compared with people born female, those born male generally need more fluid to support their increased body mass, lower average body fat, and increased calorie burn each day.

Body Weight

Hydration needs are influenced by the surface area of the body, metabolic rate, and body weight, per a paper published in the July 2016 Annals of Family Medicine. As a result, as body weight increases, fluid needs increase as well, notes the University of Missouri System.

Life Stage

Similarly, when someone is pregnant, they require additional fluids to maintain amniotic fluid levels and keep the baby growing steadily, as PennState discusses. If you're nursing a growing baby, you’ll need to drink more fluids so that your body can make enough milk, according to the Academy of Nutrition and Dietetics.

Diet Quality

As the Mayo Clinic points out, the foods you eat will also affect your hydration and the amount of fluid you’ll need to drink. For example, if you get ample fruits and veggies each day (both of which are packed with hydrating fluid), you won’t need to gulp down as much water.

Soup is another food that is fluid-rich and can help you meet your target water intake.

If you eat a lot of these foods each day, you won’t need to drink quite as much. But if your fruit and vegetable intake is low on any given day, a few extra glasses of water will compensate for the fluid you’ll miss.

Activity Level

When you sweat during exercise or on a hot summer day, you’ll need to replace the fluids you’ve lost by drinking more H2O. As the American College of Sports Medicine points out, the intensity and duration of exercise affects how much you sweat and your subsequent fluid needs. According to a study published in Sports Medicine in March 2017, genetics and how accustomed you are to a given climate can also influence sweat volume.

Unfortunately, calculating exact hydration losses from physical activity is complicated, because people sweat at drastically different rates, according to the American College of Sports Medicine. In other words, even in the exact same conditions, two people of the same gender, weight, and with similar diets will sweat differently — and thus need different amounts of fluid.

RELATED: 6 Unusual Signs of Dehydration

The Importance of Staying Hydrated

While water intake needs vary, one thing is for sure: Meeting your personal hydration needs each day will have a tremendous benefit to your health.

Indeed, as the Harvard School of Public Health points out, good hydration keeps the body functioning properly, lubricates joints, and regulates body temperature. The university also notes that good hydration helps you sleep better, think more clearly, and even puts you in a better mood!

One Last Thing: Don’t Flood Your System All at Once

Drinking water gradually throughout the day is important. Too much water at one time may increase the risk of a condition called hyponatremia, which occurs when the electrolytes in the body become depleted. As the Mayo Clinic states, hyponatremia may be life-threatening.

Water may not be the most exciting beverage in a world of iced mocha cappuccinos and matcha teas, but you literally can’t live without it. So how much water should you drink a day? Well, let’s dive into some numbers.

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The National Academies of Science, Engineering and Medicine recommends the following for daily fluid intake:

• 125 ounces (3.7 liters) for men.
• 91 ounces (2.7 liters) for women.

Here’s the thing, though: Consider those numbers a starting point.

“Your size, metabolism, location, diet, physical activity and health all factor into how much water you need,” says preventive medicine specialist Roxanne B. Sukol, MD.

And the fluid you consume doesn’t all come out of a glass. You can expect about 20% of your daily fluid intake to come from water that’s in food.

That’s a lot of information to gulp down all at once, right? Well, here’s a drip-by-drip accounting.

Is 8 glasses a day enough?

So how much water should you drink in a day? We’ve all heard that 8 glasses is the ideal. But there’s no scientific evidence that drinking 8 glasses of water is necessary.

To determine how much water you need, Dr. Sukol suggests considering these four factors:

• Activity level. If you work out a lot or are moving all day long, drink more water.
• Location. If you find yourself in a warmer climate or at higher altitudes, you’ll probably want to increase your water intake.
• Metabolism. If you think you have a speedy metabolism and your body seems to need more fuel to keep its engines revved, you may want to take some extra sips during the day.
• Size. The more you weigh, the more water your body tends to need.

But water demands are also like the stock market, with daily fluctuations that depend on:

• Alcohol consumption. Alcohol is a diuretic that can make you dehydrated. Before you decide on a second cocktail, drink a glass of water to rehydrate yourself and replace fluids caused by alcohol-mediated losses.
• Health. “We really worry when people are sick and they’re not getting a sufficient amount of liquids — especially if they are also losing fluids due to vomiting or diarrhea,” notes Dr. Sukol. If you have a fever, it’s a good idea to increase your daily quota of fluids by a few cups. Clear broth and gelatin also count as fluids.
• Physical activity. Did you go for a sweat-inducing run? The more active you are, the more water you’ll need.
• Weather. You’ll definitely need more water during a heatwave than a blizzard. Use your common sense. If you live in a dry climate or a dry home, it won’t hurt to drink a little more than the daily recommendation.

Benefits of water

Water is sometimes considered a fourth macronutrient, joining the list with protein, fats and carbohydrates. It’s required for your body to function optimally. (Fast fact: Your body is 60% water.)

“That’s why you need to make sure that you’re drinking enough water,” explains Dr. Sukol. “It’s also why people who are too sick to drink tend to get into further trouble.”

Drinking water can help your:

• Blood. Water ensures that your blood is just the right consistency to carry oxygen- and nutrient-rich blood to the areas that need it, including your brain, heart, kidneys and muscles.
• Digestive system. “Dehydration is an easily reversible cause of constipation,” notes Dr. Sukol.
• Joints. Think of your joints like the gears of your car. They need to be well-lubricated to work and last.
• Kidneys. Drinking adequate amounts of water can prevent kidney damage and disorders.
• Skin. For clear, wrinkle-free skin, drinking H2O can be just as effective as expensive anti-aging creams and lotions. It can also stave off certain skin disorders.
• Teeth. Water keeps your mouth clean and lowers your risk for tooth decay.

There’s also research that consuming water may boost exercise performance, help with weight loss and reduce allergy and asthma symptoms.

How to tell you’re hydrated enough

Even if you’re not thirsty, don’t assume you’re drinking enough water. Instead, take a peek at your urine, says Dr. Sukol. If it’s a pale-yellow color, you’re right on track. If your urine is darker or has a strong odor, then you could probably use more fluids.

Other symptoms of mild to moderate dehydration might include:

• Constipation.
• Dizziness.
• Dry mouth.
• Fatigue.
• Muscle cramps.

More severe dehydration constitutes a medical emergency that requires immediate attention. Severe dehydration can include the above symptoms as well as:

• Abdominal pain.
• Confusion.
• Lethargy.

Is water your only option?

If you’re still thinking, how much water should I drink? it’s important to kow that many of the foods you eat contain water. Some foods that are heavy on the water content include:

• Cucumbers.
• Celery.
• Iceberg lettuce.
• Zucchini.
• Watermelon.
• Strawberries.
• Cauliflower.

When it comes to other drinks, you can include milk, tea, coffee and juices and sports drinks (though watch out for all that added sugar).

So how much water is too much?

Drinking too much water is a hard to do — but it’s possible. Hyponatremia, or low sodium, can be caused by several things — but one of them is when people drink too much water over a relatively short period of time.

“This condition can be quite serious but it is extremely rare,” says Dr. Sukol. “It’s pretty unusual that anyone would drink so much water that they would actually hurt themselves.”

The bottom line? When you consider how much water to drink a day, a good piece of advice is to focus on drinking water throughout the day. Opt for a reusable water bottle and consider adding fruit or water enhancers.

How do I know if I drank too much water?

Can you drink 4 Litres of water a day?