Eight 8-ounce glasses of water a day keep the dehydration away, or so we’re told. It’s a simple rule that will definitely help you stay hydrated, but in reality, it’s not the magic number. The amount of water you really require is a lot more complex.
According to the Centers for Disease Control and Prevention (CDC), there isn’t a set amount of plain water you should sip on daily, but there are recommendations. Many factors should be considered — one size (or amount) of H2O doesn’t fit all!
Your body needs water to survive, which is a pretty big reason to stay hydrated! Our bodies consist of about 60 percent water, and our organs, cells, and tissues all require it to function properly. Research shows even a 1 to 2 percent body water loss can impair brain function.
Water also helps:
We all need different amounts of nutrients and calories, and the same goes for water. Here are a few factors to consider if you’re wondering how much water you should be drinking on the daily.
It’s no question that a kid shouldn’t need the same amount of water as an adult. The Institute of Medicine (IOM) recommends men who are 19+ drink about 101 ounces (about 13 cups) of water a day and women drink about 74 ounces (about 9 cups).
In reality, the range is huge, and some people may need more water than others, based on thirst and kidney function.
The amount is way less for a tiny human. A child who is 4 to 8 years old should drink about 5 cups (40 ounces) of water each day. For kids ages 9 to 13, the amount increases to 7 to 8 cups (56 to 64 ounces). And at ages 14 to 18, water intake should range from 8 to 11 cups (64 to 88 ounces) per day.
If you’re pregnant or breastfeeding
Water is super important for everyday body functioning, so it’s extra necessary when you’re growing a baby! During pregnancy, water is essential to form amniotic fluid and produce extra blood.
Pregnant women should strive to get about 10 cups (80 ounces) of water each day.
Keep that hydration up post-baby too! Breast milk contains high amounts of water, which keeps your baby hydrated. If you’re lacking in the water department while breastfeeding, it can affect your milk supply. The IOM recommends drinking about 13 cups (104 ounces) of water per day while breastfeeding.
Where you live
Hot and sunny weather comes with more than a tan — it also involves sweating! Sweat is the way your body regulates your temperature and keeps you cool. Staying hydrated is especially important if you’re active in this kind of weather.
If you live in or are visiting the mountains or a high altitude location, you’re also going to need more water. The higher up you go, the less oxygen there is. This makes your body work harder to maintain oxygen levels, which makes you breathe harder and use more water.
If you’re not drinking enough, your body can be down 2 to 3 liters of fluid in the first few days at high altitudes.
If you exercise (especially in hot environments)
Feel like you sweat out enough to fill a pool during an intense workout? Or notice you feel lighter after some HIIT? Well, that’s actually water loss. Long bouts of exercise in hot environments may cause more than 1 liter of body fluid to be lost each hour.
The American College of Sports Medicine recommends hydrating before physical activity to allow your body to absorb that fluid and prevent losing more than 2 percent of your body weight from water loss. To do this, drink 16 to 20 fluid ounces 4 hours before exercising.
During exercise, focus on what your thirst is telling you. If it’s a really long workout, consider choosing a beverage that has 6 to 8 percent carbohydrates.
Once your exercise is complete, be sure to drink another 16 to 24 ounces for every pound of water weight you’ve lost.
If you’re sick
Feeling sick may involve loss of appetite or things coming up (or out 💩). We’ve all heard the recommendation to “get plenty of fluids,” and it’s not wrong!
The Academy of Nutrition and Dietetics says you typically get about 20 percent of the water you need from food. If you’re not eating and you’re losing bodily fluids, your hydration level can drop quickly. It’s especially important to stay hydrated if you have a fever.
There’s not a specific amount you should aim to drink when sick — just focus on getting enough fluids without overdoing it. Aim for the amount recommended based on your age, drinking it slowly and steadily!
Unfortunately, there’s really no exact number to follow for every hydration scenario. But if you need numbers to get started, these can help:
|Demographic||How much water to aim for daily|
|men (ages 19+)||13 cups (104 ounces)|
|women (ages 19+)||9 cups (about 74 ounces)|
|pregnant women||10 cups (80 ounces)|
|breastfeeding women||13 cups (104 ounces)|
|men who exercise often||16 cups (about 125 ounces)|
|women who exercise often||11 cups (about 90 ounces)|
If you’re concerned about your hydration, work with a healthcare professional to gauge how much water is best for you.
Although plain water is the best way to stay hydrated, it’s not the only way! Everyone needs a little variety when it comes to beverages, and there are quite a few that contain H2O.
Coconut water is an alternative to water that’s also high in electrolytes (potassium, sodium, and chloride). A 2012 study found that it can be helpful for rehydration and recovery after exercise. Plus, it doesn’t contain all the sugar that sports drinks sometimes do.
Don’t discredit your morning coffee or tea either. While the caffeine technically makes them diuretics (meaning they increase the amount of water removed via your pee), your fave morning beverages still contribute to your hydration. A 2014 study actually found that moderate coffee intake can be just as hydrating as water.
Getting enough water is about more than just drinking fluids. Lots of foods can chip in too! Here are some foods with the highest water percentages:
- Watermelon (obvi) — 92 percent
- Cucumber — 95 percent
- Lettuce — 96 percent
- Strawberries — 91 percent
On the flip side, not getting enough water is bad news and can lead to dehydration.
When you’re dehydrated, your body essentially doesn’t have enough water and has lost way more water than you’ve consumed.
If you’re mildly dehydrated, you may experience these symptoms:
- trouble thinking clearly (as a result of reduced brain function)
- extreme fatigue
- dizziness or lightheadedness (with or without a headache)
- dry mouth
- dull, itchy skin
If you’re severely dehydrated, you may also experience:
- overheating (as a result of unregulated body temperature)
- kidney stones
- low blood pressure
- lack of sweating
- extreme thirst
- really dark pee
If you’re mildly dehydrated, just drinking more water should help get your levels back to normal. But if you’re severely dehydrated, you may need to see a doctor ASAP and will probably need intravenous (IV) fluids and salts at the hospital.
You can have too much of a good thing! While water is very important, it can also be life threatening if you drink way more than you need.
If you drink too much water, you basically dilute your electrolytes (which help balance fluids inside and outside your cells). This decreases the sodium levels in your blood, which can cause hyponatremia.
Hyponatremia is serious and can cause:
- brain swelling (leading to headaches, nausea, and vomiting)
- muscle weakness, spasms, or cramps
- extreme fatigue
- double vision
- increased blood pressure
Athletes may experience overhydration more often because they may drink a lot of water in a short amount of time. A complicating factor in this scenario is that symptoms of hyponatremia can be similar to those of heat exhaustion or stroke, which may lead some people to drink even more water.
As long as you’re focusing on unsweetened drinks and choosing a good variety of foods that have high water content (fruits and veg), odds are your hydration levels are good to go!
The Academy of Nutrition and Dietetics also has a few tips to ensure your water intake is up to par:
- Listen to your body. Basically, if you’re thirsty, drink!
- Be consistent. Drink water throughout the day, not at just one time. Have it at meals and between meals.
- Water bottle up! Carrying a refillable water bottle is a handy way to ensure you’ll have water when you need it.
- Enhance it. Plain water can get boring — we get it. Enhance that flavor with fresh fruit juice or even herbs.
This is a lot to take in, but don’t overthink it. Aim to get in the recommended amount of water for your age, and then make adjustments based on factors like your activity level, where you live, and whether you’re sick.
Your body will let you know if it’s thirsty, and you can keep an eye on that pee color to check. If you’re worried and noticing signs of dehydration or overhydration, don’t hesitate to call your doc or take a trip to the ER.
Stay hydrated, friends!