How Much Water Should I Drink a Day?

by Owala Team

Updated: August 26, 2025

The 8x8 Rule—Is It Right?

You’ve probably heard the classic advice: drink eight 8-ounce glasses of water a day (64 ounces total). Pretty easy to remember, right?

But get this… there’s no actual science to back up the 8x8 rule. If your brain just exploded, we get it. Ours did too when we found out.

How Much Science Says You Should Drink

The U.S. National Academies of Sciences, Engineering, and Medicine suggests a daily intake of:

15.5 cups (3.7 liters or 124 ounces) for men
11.5 cups (2.7 liters or 92 ounces) for women

Where to Begin

Start Measuring Your Water

A water bottle is by far the easiest way to do that. Whether you want a lightweight one for travel (like a 24 oz.) or a hefty size that lets you drink a lot at once (like 40 oz.), all you have to keep track of is how many times you’ve refilled it. Easy peasy.

Would rather measure in cups? Here’s how many cups are in a water bottle.

Calculate Your Hydration by Body Size

Because a 200-pound person’s hydration needs more than a 160-pound person.

To find a guideline for your weight, check out our “How Much Water Should I Drink?” chart. This chart provides personalized intake suggestions based on body weight. Here are a couple of examples:

200-Pound Person: Aiming for 100 ounces of water a day means five 24-oz. Owala bottles or three 32-oz. bottles.

160-Pound Person: At 80 ounces a day, that’s four 24-oz. bottles or three 32-oz. bottles.

Want to know your exact hydration needs? Try out our Hydration Calculator.

Factors Affecting Your Hydration Needs

1. Where You Live

It’s not just about temperature—it also comes down to altitude. Where you live can benefit or zap your hydration levels.

Hot, dry, or humid climates: The more you sweat, the more water you need to make up for it.
High altitude: Higher altitudes cause dehydration because of increased urination, dryer air, and rapid breathing.
Cold weather: It actually suppresses thirst cues and pulls moisture from your lungs (especially if you’re in high altitudes…we’re looking at you, ski towns).

If you’re dealing with one or more of these, you’ll need to up your hydration to compensate. For serious cases of dehydration, you’ll want to give your water a little extra power up.

2. Your Diet

Ever had something to eat that immediately makes you want to chug a glass of water? Those can definitely mess with your hydration levels. For example, if your food or drink is…

Salty: Fries, crackers, or other salty snacks dry out your mouth and absorb fluids during digestion.
Spicy: It won’t just make your mouth burn—it’ll also mess with digestive fluids.
Sugar-y: Might not make you immediately thirsty, but has the same digestive effects as salty and spicy foods.
Caffeinated: Caffeine acts as a diuretic, increasing urine output by boosting blood flow to the kidneys, which results in fluid loss.

Drink an equal amount of water for every caffeinated beverage, like coffee or tea, to stay balanced. You can also eat hydrating foods like fresh produce. Low-calorie options like celery, cucumber, or watermelon are nutrient-rich and high in water, making them awesome choices for hydration.

3. Temperature and Time Outdoors

During warmer months, you need to increase your water intake to replace fluids lost by perspiration.

If you spend a lot of time outside in the sun, you'll also need to drink extra water. Doubly so if you work outside and your job is physically taxing. It’ll help prevent dehydration and heatstroke.

4. Pregnancy and Breastfeeding

Pregnancy: 12 cups (96 fluid ounces) of water per day.

During pregnancy, your body is literally growing a human with your reserves of water, electrolytes, and nutrients. Of course you need more.

Breastfeeding: 14 cups (112 fluid ounces) of water per day.

When a woman breastfeeds, her body uses water to make milk. Make sure to take care of yourself too and replenish your water levels.

5. Overall Health

Your body’s unique needs will also have an impact on your numbers.

Illnesses (fever, vomiting, diarrhea): If you have an infection, you need extra reserves to fight the illness. If you have vomiting or diarrhea, you’re losing liquids fast.
Conditions: Diabetes and other conditions might mean you need to drink more water than the average person.
Medications: The list is too long to name, but ask your doctor about potential side effects of medications you’re prescribed. They might be dehydrating.

Tips to Drink More Water Daily

Know When Hunger is Really Thirst

Often when we reach for snacks, we're actually craving water. Try drinking first. Then you'll be able to tell if you're actually hungry, or if you're just a little dehydrated.

Avoid Drinking Too Much Water

If you drink too much water, your body can't regulate your sodium levels. This can lead to a condition called hyponatremia. Don't panic, though—it’s really rare—so if you just guzzled a lot of water, you’re probably still good.

When in doubt, use your water bottle to take the guesswork out of hydration (and check out the chart above).

Establish a Daily Hydration Routine

When you drink your daily water may be almost as important as how much you drink. Drinking it all in one go is clearly not a good idea. But when should you grab your Owala bottle and replenish your water supply?

Start off by hydrating as soon as you wake up. This can help with any overnight dehydration.
Try drinking between meals, rather than with them. Drinking water with your meals can dilute your digestive juices. Hold off drinking for half an hour before and an hour after eating.
Drink water before you go to bed. It’ll help you from getting dehydrated in your sleep.

Hydrate for Exercise

When you work out, your body isn’t just sweating—it’s also pulling water from its reserves to keep your joints cushioned and your muscles fueled. Translation?

You need to replace what you lose.

Drink up. Two cups (16 oz) every 15–20 minutes of intense exercise. If you’re more of a marathon runner or gym warrior type, drinking a gallon of water a day can really boost recovery and overall health.
Electrolytes. If you do an hour or more of intense activity consecutively, grab a sports drink. If not, skip the drink. Food actually gives you plenty of essential salts and electrolytes.

Make Water Less Boring

Is drinking plain water a drag? Don't give up—flavor it instead!

Drop in a slice of lemon, lime, orange, or even strawberries in your water. This extra fruity flavor will have you reaching for your water a whole lot more. It also has a surprising amount of health benefits.

If you’re not really a flavored water fan, we’ve got some good news: sip on some sparkling water instead. While not every water bottle can handle the pressure of carbonation, the FreeSip Twist can. It’s leakproof, fizz friendly, and is sleek enough to fit easily into your bag so you can bring it anywhere.

How Many Water Bottles Should I Drink a Day?

Knowing how much water you need to drink a day is one thing—actually drinking it is another.

But hey, that's what we're here for. When it comes to water consumption and finding a simple and effective way to track your intake, we have your back.

Owala insulated stainless steel water bottles come in five different sizes: 18 oz., 24 oz., 30 oz., 32 oz., and 40 oz. Here’s how many you’ll need to hit the recommended daily amount.

18 oz

Ladies: 5 bottles
Gents: 6.5 bottles

24 oz

Ladies: 4 bottles
Gents: 5 bottles

32 oz

Ladies: 3 bottles
Gents: 4 bottles

Tracking your water consumption by bottles is way easier than ob sessing over fluid ounces. Plus, your water bottle becomes your new supportive BFF (which is why you want only the best).

What Are the Health Benefits of Drinking Water?

As you can imagine, drinking water has a ton of health benefits. Your body is 60% water, and everything in your body runs better when you have enough of it.

For one, without proper hydration throughout the day, your brain function and energy levels start to suffer. And that's not just speculation—there are tons of studies that back this up.

The Journal of Nutrition looked at the effects of mild dehydration on young, healthy women. Conclusion? The 1.36% fluid loss after exercise impaired concentration, lowered mood, and increased the frequency of headaches.
Cambridge University studied the effects of mild dehydration on cognitive performance and mood in young men. This study found that dehydration degraded specific aspects of their cognitive performance and also increased their fatigue, tension, and anxiety, both at rest and during exercise.
The Journal of Strength and Conditioning Research’s clinical study found that a 1% loss of body water reduces muscle strength, power, and endurance.

On the flip side, many common health problems respond well to increased water intake. Here are some pro tips.

Constipation. Can be eased with extra water and foods that are rich in water, like fruits and vegetables.

Infections. Prevents recurring urinary tract and bladder infections, and decreases the risk of kidney stone development.

Skin. The more hydrated your skin is, the better and healthier it looks—and there’s less chance of breakouts.

How Do I Know If I'm Drinking Enough Water?

Trying to hit the amount of water that the U.S. National Academies of Sciences, Engineering, and Medicine recommends—listed above—is a good starting point.

But as we mentioned, there are many factors that affect how much water you should drink.It's important to observe your body's reactions to your fluid intake and adjust accordingly.

Easy ways to check:

Urine is colorless or light yellow
You rarely feel thirsty. (In terms of thirst, we're talking serious, mouth-drying thirst.)

Though it may seem like common sense, quench your thirst as soon as your body tells you to.

Best ways to stay on top of hydration:

Carry a water bottle with you and sip it throughout the day.
Drink a glass of water with each meal.
Drink water before, during, and after exercise. Aim for two cups every fifteen to twenty minutes.
If you consume any kind of performance-enhancing drinks, protein shakes, or electrolyte drinks, make sure to drink an equal amount of water.

How Much Is Too Much Water?

So how much water is too much water? Is there even such a thing?

Technically yes—but it's rare for the average human. Overhydration usually happens during sporting events, endurance training, or military training.

Overhydration and water intoxication happens when people drink more water than their kidneys can get rid of. Both the volume of water and time play a factor in this. To avoid overhydration, try not to drink more than one liter of water per hour. If you’re doing intense exercise, reach for electrolyte drinks—they’ll help your sodium levels bounce back fast.

The Final Answer

So… how much water should you drink a day? The “official” answer depends on a lot of things. You’ll want to start with the recommended amount, then adjust based on your specific needs and listen to your body.

Even if the answer isn't super simple, upping your water intake is. Carry a water bottle with you all day and sip often.

If you want the ultimate hydration sidekick, check out our full lineup of Owala water bottles. They come in fun colors (and some epic limited edition designs). But hurry—these bottles sell out fast, so if you like what you see, don’t wait!