Do You Really Need to Drink a Whole Gallon of Water a Day? Here’s What Experts Say

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By now we’re all pretty familiar with the importance of staying hydrated throughout the day. But what does “staying hydrated” even mean? Although there’s no consensus on how much water people should drink each day, the Centers for Disease Control and Prevention (CDC) and the Food and Nutrition Board (FNB) say each person’s guide should be their own thirst. If you’re feeling parched, drink some water—simple as that. As a very general guideline, the FNB suggests women should drink around 2.7 liters of water daily and men around 3.7 liters. Many folks opt to aim for the nice, square number of 1 gallon of water a day (for reference, 2.7 liters equal about 0.7 gallons), so we looked into the health benefits of drinking that much H20, from speeding up metabolism to preventing headaches.

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5 Health Benefits of Drinking a Gallon of Water a Day

1. It might improve your metabolism

Anyone who’s ever tried to drop a few pounds knows that, alongside a healthy diet and consistent exercise, hydration is key. Drinking water (approximately 20 ounces) can increase your metabolic rate by 30 percent, according to a study in the Journal of Clinical Endocrinology and Metabolism.

2. It might prevent headaches

Dehydration is one of the leading causes of that throbbing pain in your skull. Think of a constant stream of water as a measure that helps prevent a headache from developing. (Just be sure you keep sipping throughout the day.)

3. It can help flush toxins from your body

It’s all about keeping your small intestine hydrated and your body’s water balance in check. Your gastric emptying rate (i.e., how much you pee) is accelerated by how much water you consume. The more you pee, the more toxins you flush out. It's as simple as that.

4. It helps clear Brain Fog

According to a 2019 study, research shows that dehydration has “negative effects on vigor, esteem-related affect, short-term memory, and attention” and, “rehydration after water supplementation improved fatigue, TMD, short-term memory, attention, and reaction.” Makes sense considering water makes up 75 percent of the brain.

5. It helps keep you regular

Water is necessary to keeps things flowing through your gastrointestinal tract to prevent constipation. When there is not enough water available, stool becomes dry and more difficult to move through the colon, resulting in the dreaded constipation.

Do You Need to Drink a Gallon of Water a Day?

The short answer is, probably not. Hydration is crucial, but a gallon is, for most folks, a little more than necessary to stay hydrated. While drinking more water than your body technically requires shouldn’t be bad, a Dutch study found that drinking more than your body’s required amount of water didn’t have any more benefits than drinking just enough. You should drink when you’re thirsty, and if that means drinking a gallon a day, great. If it means a little less, that’s also great. If you’re not sure how much water you should be drinking, consult your doctor.

Can Drinking a Gallon of Water a Day Be Harmful?

According to the experts at Cleveland Clinic, drinking a gallon of water a day isn't harmful—with a few exceptions. "[For] those who have congestive heart failure or end stage kidney disease, sometimes water needs to be restricted because the body can’t process it correctly." If you or anyone in your care falls into one of those groups, talk to your doctor about how much water you should (or shouldn't) be drinking. Otherwise, there's no harm in chugging along—literally.

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7 Things That Might Happen if You Drink a Gallon of Water a Day

1. You might feel bloated…initially

If you’re suddenly increasing your water intake, you may feel uncomfortably full to start. Don’t worry: This will subside soon, but in the meantime, sip your water slowly and steadily throughout the day instead of all at once to minimize the discomfort.

2. You’ll have to pee all the time

Once that de-bloating kicks into gear, you’ll be flushing out the excess sodium your body is holding onto. You’ll also be doing that other bathroom business regularly, now that your body is breaking down its food more easily. And the last bonus? Those frequent bathroom breaks ensure that you’re moving around more throughout the day.

3. You might eat less

There’s a reason why nutritionists suggest chugging a glass of water before meals. It makes you feel fuller, which keeps you from consuming too many superfluous calories.

4. You might have better workouts

Water helps to transport oxygen and glucose through your body, so you’ll have more energy during your workout. Plus, it acts as a lubricant for your joints and muscles. Make sure to drink frequently two hours before your workout, every 20 minutes during and directly afterward to keep your body properly hydrated.

5. You might lose weight

Think about it: You’re peeing away the extra bloat, you’re eliminating waste regularly, you’re eating less and you’re working out more efficiently. While drinking more water in itself won’t make you lose weight, the positive side effects just might.

6. Your under-eye circles might go away

Under-eye bags are commonly caused by the retention of water to that delicate area. Whether it’s from eating a salty meal or a late-night sob-fest, sodium is prone to pooling. Drinking more water will help flush out the excess salt from your system, which will tamp down any puffiness—even there.

7. You’ll find yourself craving more water

The more you drink it, the more you’ll want it--and the less you’ll crave other not-as-great-for-you beverages. Luckily, the stuff is free, pure and as evidenced above, the absolute best for you.

Compassionate Eye Foundation/David Oxberry/getty images

7 Ways to Drink More Water

1. Make it part of your morning routine

Having a glass of water as soon as you wake up is great for a host of reasons (including boosting your immune system and metabolism), but it also sets you up for a day of top-notch hydration. Before, or—fine—while you make your first cup of coffee or tea, have a glass or bottle on hand to start the day off right.

2. Set a specific goal

Being deliberate about what you want to accomplish makes you way more likely to actually accomplish it. Instead of saying, “I’m going to drink more water,” think about how much you’re currently drinking and come up with an exact number of ounces (or bottles) that you’d like to get to.

3. Buy a pretty water bottle

Superficial? Yes. Effective? You bet. Buy a bottle you’re happy to drink from and you’ll use it more often—simple as that.

Shop water bottles: Pogo Sport Water Bottle ($10); w&p Porter Water Bottle ($30; $24); Anthropologie Monogram Water Bottle ($32)

4. Eat water-filled foods

Cucumbers, grapefruit and watermelon aren’t only delicious snacks—they can also help keep you hydrated throughout the day. We’re not saying you should count solely on food for hydration, but it’s a great way to sneak some extra water into your system.

5. Use an app to track your progress

We use apps for almost everything, so why should staying hydrated be an exception? Apps like Waterlogged (for iPhones) and Hydro Coach (for Android) make it easy to stay on track with your water-drinking goals.

6. Set an alarm on your phone

At first, your coworkers might be annoyed by the alarm that goes off on your phone every hour on the hour signaling it’s time to hydrate. Before long, though, your body will get used to the schedule and you’ll be able to ditch the blaring reminder altogether.

7. Make water more enticing

Some people genuinely like drinking water. Others, not so much. If you’re in the latter camp, try spicing your bottle up with natural flavors. Fruits, veggies and herbs are all great options for adding a little oomph to your H20 without adding tons of calories or sugar. Lemon-and-basil water, anyone?

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Sarah Stiefvater

Wellness Director

Sarah Stiefvater is PureWow's Wellness Director. She's been at PureWow for ten years, and in that time has written and edited stories across all categories, but currently focuses...
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