How Much Water Should I Drink a Day?

Drinking water is essential—we simply wouldn't survive without it. But that's not all hydration is about. These days, everyone seems to carry around their own customized water bottle and use it to stay hydrated throughout the day. Yes folks—drinking water is trendy. Hydration is cool.

This is great news (and we're not just saying that because we make water bottles). Drinking plenty of water is one of the best things that we humans can do for our health.

But this also begs the question: how much water should I drink a day? How much is too much? 

Never fear—as water bottle experts, we're here to answer these questions and more in this complete guide to improving your daily fluid intake. 

How Much Water Should I Drink a Day? 

Surely you've heard the advice to drink eight cups of water a day. That means drinking eight cups containing eight fluid ounces each, for a daily total of 64 fluid ounces. Commonly known as the "8x8 rule," it's an easy tip to remember. 

However, you might be surprised to learn that this is a completely arbitrary number. That's right, there's no actual science to back up the 8x8 rule! 

So now you're wondering: how many ounces of water should I drink per day?

The U.S. National Academies of Sciences, Engineering, and Medicine determined that the adequate daily fluid intake for an average, healthy adult living in a temperate climate is: 

  • 15.5 cups (3.7 liters or 124 fluid ounces) of fluids per day for men 
  • 11.5 cups (2.7 liters or 92 fluid ounces) of fluids per day for women

About 20 percent of this should come from foods that are high in water. Fruits and vegetables, both fresh and cooked, are excellent sources of fluids. The other 80 percent should come from beverages.  

This is an excellent general recommendation, but it's only that. A more in-depth answer to the question of how much water do I need is that it varies based on several factors. You might need more or less water than the average person, depending on your environment, your activity level, your overall health, and more. 

Where You Live

The first factor in determining how much water you should consume is where you live. If you're in a dry, humid, or hot area, you're going to sweat more per day than the average person. That means you'll need to drink more water to replenish your body's supply. 

You also need to drink more water if you live in the mountains or at a high altitude. Higher altitudes can cause dehydration as a result of increased urine output, dryer air, and rapid breathing. 

The colder temperatures that are often found at higher altitudes actually suppress the body's thirst response. Cold temperatures also make your kidneys conserve less fluid, leading to more frequent urination. 

Dry, cold air also absorbs moisture from your lungs, which further contributes to fluid loss. You need to consume more than the average recommended amount of water to maintain your body's fluid levels. 

Your Diet

The second determining factor for how much water you should drink is your diet. If you consume a lot of caffeinated beverages, you'll need to drink more water to balance them out. 

This is because caffeine is a diuretic. Diuretics are substances that stimulate your body to produce more urine than normal. Caffeine does this by increasing the blood flow to your kidneys, which makes them release more water. 

A good rule of thumb is that every time you drink a caffeinated beverage like coffee or tea, you should drink an equal amount of water. 

If your diet is high in spicy, salty, or sugary foods, you'll also need to drink more water than the average person. This is because salt, sugar, and most spices absorb fluid in your digestive tract. You have to drink more water to offset the amount that these tasty, absorbent flavorings take away. 

Temperature and Environment

Temperature and environment are both huge factors in determining water intake. During warmer months, you need to increase your water intake to replace fluids lost by perspiration. 

If you spend more time in hot temperatures or outside in the sun, you'll also need to drink extra water. This is especially relevant for people who work outdoors—and doubly so if your job is physically taxing. Increasing your water intake helps prevent dehydration and heatstroke. 


Replenishing the water your body loses during exercise is crucial. Beyond sweating, your body uses its water reserves to cushion your joints and supply blood to your muscles. Aim to drink about two cups, or 16 fluid ounces, for every fifteen to twenty minutes of intense exercise.

You're probably aware that you need to replenish your body's electrolytes after exercise as well. While this is true, you'll get most of the electrolytes and essential salts that your body needs from your regular food. You only need to add electrolyte-boosting sports drinks if you do an hour or more of consecutive intense physical activity. 

Pregnancy and Breastfeeding 

Women who are pregnant and breastfeeding also need to increase their water intake. During pregnancy, your body is supporting an additional human with your reserves of water, electrolytes, and nutrients. Pregnant women should aim to drink about 12 cups, or 96 fluid ounces, of water per day. 

When a woman is breastfeeding, her body uses water to make milk. This is why breastfeeding can leave you feeling dehydrated. If you're breastfeeding, aim to drink 14 cups, or 112 fluid ounces, of water per day. 

Overall Health 

Many illnesses cause you to lose fluids and potentially become dehydrated. If you have an infection or fever, you need to drink more water so that your body has extra reserves to fight the illness. This is also the case if you are losing fluids to vomiting or diarrhea. 

People with diabetes also need to drink significantly more water than the average person. Additionally, some medications can act as diuretics, in which case you need to increase your water intake as well. 

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. And unless you measure your water out cup by cup, it can be hard to keep track of how much you drink.

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 are available in three different sizes—and based on the size of your bottle, we'll give you a simple calculation for how many bottles of water you need to drink a day. Our insulated bottles come in 19-oz., 24-oz., and 32-oz. sizes (note that the Tritan option is available exclusively in a 25-oz. size, but since that's only one ounce more than our medium insulated bottle, we'll stick with the three insulated bottles as a guide).

OK guys and gals, here we go. Let's say you like to drink from one of our 19-oz. bottles. To hit the daily recommended amount of water, gals need to drink about five bottles over the course of a day, and guys need to drink about six and a half. 

With the 24-oz. size, you're looking at about four full bottles for gals and five for guys. 

With our 32-oz. bottles, the gals should drink about three and the guys about four full bottles.

Tracking your water consumption this way is far more intuitive than measuring out every single fluid ounce. Plus, your water bottle starts to feel like a helpful, healthy-hydrating friend!

What Are the Health Benefits of Drinking Water?

As you can imagine, drinking water has a ton of health benefits. Your body is 60 percent water after all, and water is an important component in nearly all of your body's processes. You need to drink up!

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. 

One study published in the Journal of Nutrition examined the effects of mild dehydration on young, healthy women. The study concluded that a fluid loss of 1.36 percent after exercise impaired concentration, lowered mood, and increased the frequency of headaches. 

Another study conducted by Cambridge University examined 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. 

Even mild dehydration hurts your physical performance. A clinical study published in the Journal of Strength and Conditioning Research found that a one percent loss of body water reduces muscle strength, power, and endurance. 

On the flip side, many common health problems respond well to increased water intake. For example, constipation can often be eased by drinking more water and eating foods that are rich in water, like fruits and vegetables. 

Increasing water consumption also helps prevent recurring urinary tract and bladder infections, and decreases the risk of kidney stone development. 

Several studies show that increased water intake helps with skin hydration. The more hydrated your skin is, the better and healthier it looks. There is evidence to suggest that drinking more water also helps decrease the frequency of breakouts, but more research is needed to determine water's specific effects on acne. 

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 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. 

Two signs that your water intake is adequate are if your urine is colorless or light yellow and if you rarely feel thirsty. (In terms of thirst, we're talking serious, mouth-drying thirst.)

Though it may seem like common sense, drink water when you feel thirsty. Most of the time, the sensation of thirst is your body's way of telling you that it's already dehydrated. Drink water as soon as possible to dig yourself out of the dehydration hole. 

The nest way to ensure that you're getting the proper amount of fluids, regularly, is to carry a water bottle with you and sip it throughout the day. You should also make a habit of drinking a glass of water with each meal. 

Drink water before, during, and after exercise, too. 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 rarely a problem for healthy adults. It's extremely difficult to consume too much water by accident. 

Drinking too much water, also known as water intoxication, typically affects athletes participating in sporting events or endurance training. It can also affect soldiers during military training. 

Overhydration and water intoxication occur when people drink more water than their kidneys can get rid of. Both the volume of water and time play a factor in this. 

According to a 2013 study, your kidneys can eliminate between 20 and 28 liters of water a day. However, they can remove no more than 0.8 to one liters per hour. 

To avoid overhydration, try not to drink more than one liter of water per hour. If you're participating in a sporting event, endurance training, or any other seriously extended physical activity, replenish your blood's sodium levels with electrolyte-rich drinks. 

Stay Hydrated!

The question of how much water should I drink a day doesn't have a single, straightforward answer. Yes, drinking the recommended average amount is great, but you also need to listen to your body and be aware of your specific needs. 

But even if the answer isn't super simple, the solution to increasing your water intake is. Carry a water bottle with you all day. When you feel thirsty, drink up! 

Ready to hydrate? Check out our full lineup of Owala water bottles and find the one that best fits your personal style. After all, it's going to be by your side all the time—just like a trusted best friend. We even offer special seasonal colors, if you want a bottle bestie that's a bit more exclusive. But hurry—these bottles sell out fast, so if you like what you see, order your Owala bottle today!