Health

Here’s Exactly How Much Water You Should Drink Every Day

You can stop obsessing over eight glasses a day now, k?
Glass of water on colorful background
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It’s not uncommon to stop and wonder, “How much water should I drink?” The question might cross your mind when your fitness tracker buzzes, or it could occur to you when you’re a little thirsty. Even if you’re diligent about drinking water throughout the day, you might still have questions about whether or not you’re drinking enough. Sometimes it seems like we're all supposed to be drinking more water than we currently are, no matter what health or fitness goals we might have. In fact, it seems like the "drink more water" imperative applies even when you don’t have a specific health goal in mind. But the question is: How much is enough? I'm happy to report that you don't have to do the guesswork anymore. We spoke with experts to explain exactly how much water you need, some surprising ways to get it, and when you should be worried about dehydration.

First, let’s talk about the benefits of water.

Before we get into how much water you should be drinking, let’s talk about why human beings need water in the first place. Yes, it’s obvious that consuming water keeps us alive, but what does it do specifically? Well, according to the Mayo Clinic, our body weight is made up of somewhere between 50 and 70 percent water. So, as you can imagine, water plays a major part in all bodily functions. It helps remove waste through urine and sweat. Water also regulates your body temperature, and it helps cushions your joints, the Mayo Clinic explains. The benefits of water extend far beyond these—pretty much every organ and cell in your body needs water to function.

This is how much water you should drink a day (and a few factors that impact your intake).

You've probably heard you're supposed to drink at least eight 8-ounce glasses of water daily. That's almost enough to fill a two-liter bottle—which even the most type-A people may find daunting. But that classic advice can be a little misleading.

"Fluid requirements vary among individuals based on age, sex, activity level, and even where you live," Jessica Fishman Levinson, M.S., R.D., C.D.N., a nutrition counselor, tells SELF. So, how much water you should drink every day may actually vary each day, depending on the other things you're doing, eating, and drinking.

The Institute of Medicine of the National Academies of Sciences actually suggests that adequate water intake includes 2.7 liters (11 cups) to 3.7 liters (almost 16 cups) per day. But there’s good news: They don’t say you need to drink all of that each day. Here's the deal.

Food and other liquids count toward your daily water intake.

If 11-16 cups of water sounds like a lot, you’ll be relieved to know that all fluids count toward your daily intake, not just plain old H20. That includes all sources of water—from a basic glass of tap, to a cup of coffee, to the water content of the foods you eat (which, the Mayo Clinic estimates, makes up about one-fifth of your daily fluid intake).

According to the Mayo Clinic, the benchmark should really say "eight 8-ounce glasses of fluid," not water, because drinking things like milk, tea, and juice contribute to your total. "Good options for hydration without added calories are waters infused with fruit and herbs, unsweetened tea, and sparkling water," Levinson says.

"Your body absorbs water in foods just like it would liquids," Levinson explains. Many fruits and vegetables have high water content, the Mayo Clinic says. Some good options: watermelon (duh), cucumbers, lettuce, celery, tomatoes, strawberries, oranges, and grapefruit. Even soup and popsicles count as fluids.

Some foods and beverages work against you, though.

If you’re a coffee-lover, there's some great news: As we mentioned above, coffee does, technically, contribute to your daily water intake. The rub, however, is that caffeine is a diuretic, which means that when you drink coffee, you probably end up peeing more than you typically would. So, whatever water you get from the coffee is likely balanced out by the extra peeing. Another common diuretic? Alcoholic beverages. This means that you can’t exactly count your nightly glass of red wine as a source of water. In fact, it’s best to remember to stay hydrated with actual water while drinking alcohol.

"Foods with a diuretic effect may cause you to excrete more water, so you may need more," Levinson says. If you eat high-sodium foods, as another example, your body likely will retain more water, leaving you thirstier. Drinking more fluids will help dilute your system and get fluids moving regularly again.

So, how can you tell if you're getting enough water?

Since you're not always keeping track of these sneaky sources of fluids, the best way to gauge your daily water intake is by how your body feels. More specifically, when you tune into your body—eating when you feel signs of hunger and drinking when you’re thirsty—there’s a solid chance you’re going to get what you need, or pretty close to it. So it may work for you to stop worrying about the whole eight glasses a day thing and think about it this way instead.

It's also important to make a conscious effort to drink more whenever you're getting sweaty. Along with food, water is the fuel that powers your workouts. As you sweat, you're literally losing water, and you have to replenish it as you go. Aim to drink one or two cups of water before you exercise or do work in the heat, and sip about a half to one cup of water every 15 minutes while you're working out. If you're sweating really hard, or if you're out in the heat, you might need more—listen to your body. You can even use a hydration pack so that you’re able to drink while you're hiking, working in the heat, or running long distances.

You don't need to think too much about hitting a particular number of cups/liters/gallons/bottles of water each day, but it can be helpful to get in the habit of drinking more regularly throughout the day, even before you’re thirsty. Yes, if you're thirsty, your body's telling you that you need more water. But this also means you could already be dehydrated, Levinson explains. To make sure you're hydrated, keep a refillable water bottle with you all day so you can constantly sip whenever you want. For more tips, check out these 22 easy ways to drink more water every day.

Another good way to determine your fluid status is by taking a peek inside the toilet after you pee. "If your urine is light yellow, you're probably getting enough fluids. If it's dark or smells strongly, you probably need more water," Levinson says.

Here are some subtle signs that you’re not drinking enough water:

If you’re not drinking enough water, you run the risk of dehydration. Some of the signs of dehydration are fairly obvious—but others aren't. If you're thirsty, you should drink. That's a no-brainer. But, for some folks, dehydration doesn’t always include feeling thirsty. There are a few other signs of dehydration that aren’t as obvious.

1. You’re feeling super dry.

When your body is begging for hydration, the need can manifest in various signs of dryness, including dry mouth, chapped lips, dry skin, reduced sweating, and a lack of tears.

2. You feel faint, light-headed, or you have headaches.

Doctors aren't quite sure why, but they think it might be because when hydration levels drop, so does blood volume, which can reduce oxygen supply to the brain, the Merck Manual explains.

3. Your muscles feel weak or crampy.

Cramping, muscle spasms, and generally feeling weak or fatigued can all be indications of dehydration.

4. Your breath is randomly stinky.

Having bad breath can be a tip-off that you need to sip some water. That goes with the dry mouth thing: Saliva has bacteria-fighting properties; when your saliva levels go down, so does your mouth’s ability to fight odor-causing germs.

5. You feel confused.

In addition to the above, confusion and delirium can all be signs of severe dehydration, the Mayo Clinic explains. If you have these symptoms, you should reach out to your doctor immediately.

In rare cases, you can also overhydrate.

Most people aren’t at risk for overhydration, but it's more likely to occur during endurance activities, like running a marathon. Additionally, overhydration is more likely in older people because kidney function becomes less effective as you age, the Merck Manual explains. (Your kidneys are responsible for filtering waste and fluids from the body, the Mayo Clinic explains.) Overhydration can cause a condition known as hyponatremia, which happens when the sodium levels in your bloodstream become unusually low, leading to your cells becoming waterlogged, the Mayo Clinic explains. Signs include feeling nauseated, confused, run-down, and irritable. Overhydration can also cause seizures and put you into a coma if it’s not caught in time.

For athletes that are worried about overhydration, your best bet is to take strategic water breaks (instead of guzzling fluids to avoid dehydration). The National Association of Sports Medicine (NASM) recommends you drink 14-22 ounces of fluid two hours before rigorous activity, rehydrate at least every 20 minutes while working out, then drink some more when you’re done. Those are just general guidelines, so experiment to figure out what helps you feel hydrated enough without feeling too full of liquid. If you’re exercising for an hour or less, water should do the trick, but if you’re going for longer, you might consider a sports drink, NASM explains.

Finally, a quick note about the idea that drinking more water can help you lose weight:

You may have heard this thrown around from time to time, so we figured we'd clear the air. Staying hydrated is great for all sorts of reasons, from preventing headaches to helping you crush your workouts. But if losing weight happens to be a goal of yours, just know that drinking a ton of water isn’t some magical key to weight loss. That said, for some people, thirst and hunger cues are easy to confuse. If you’re feeling famished and you’re not sure why, using the above methods to determine if you’re getting enough water (like checking your pee) is one step you can take, along with things like making sure you’re actually eating enough and remembering that pandemic stress can naturally have an effect on your appetite (and that there’s nothing wrong with that). Aside from that, you should aim to get enough water because it helps you feel great—end of story.

Related:

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  3. This Water Bottle for Kids Is the Only One My Lazy Adult Self Knows How to Clean