How Much Water Should You Drink Daily? How to Stay Hydrated?

How much water did you drink today? Did you struggle to finish a glass, or did you carry a Stanley cup around all day and down it several times in a row? Much of the U.S. is still experiencing dangerous heat waves, with temperatures near or above 100 degrees Fahrenheit. That kind of extreme heat can lead to particularly risky health conditions, like irregular heartbeats and high blood pressure. That means it’s more important than ever to stay hydrated.

There’s a lot of advice out there about hydration, which can be confusing. In this article, we’ll explain how to figure out how much water you should drink, what influences your needs, and four rules of thumb for hitting your hydration goals.

Want more tips? Find out which foods can help you stay hydrated, how to sleep well on hot nights, and which electrolyte hacks you should start using today.

How much water should you drink per day?

We’ve all heard the old adage: Drink eight eight-ounce glasses of water every day. It’s the eight-by-eight rule that tells us to drink 64 ounces (about 1.9 liters) of water every day. Many of us have blindly followed this advice our entire lives, without knowing where it came from or why we need eight glasses of water.

Read more: Best Reusable Water Bottles

Apparently the eight-by-eight rule came out of nowhere, because there is no scientific evidence to support it. It’s just another one of those Long-standing myths that people believe because that’s what everyone believes. Drinking 64 ounces of water a day isn’t bad, but it can be too much or too little for some people.

Other guidelines exist, but there is still no real consensus. There is no formal recommendation for how much water people should drink each day, perhaps because everyone needs a different amount of water.

There is an “adequate intake” of water for adult men and women, but it can vary from person to person. This adequate intake includes water from non-aqueous beverages, such as milk, sports drinkstea and yes, even coffee. It also contains water from fruits, vegetables, and other foods (think of how much water is in a bowl of oatmeal or soup).

The sufficient intake is 15.5 cups (3.7 liters or 125 ounces) for men and 11.5 cups (2.7 liters or 91 ounces) for women. How you choose to consume these 125 or 91 ounces of fluid is up to you. While these are the closest to a recommended daily intake, even these numbers will vary for each person based on their health status.

You may need more water if…

You have an active job: People who are on the go all day (especially those who work outside) may need more water than most. The more you move, the more you sweat, and you need to replace lost water (and electrolytes) through fluid intake.

If you’re working outside during a heat wave, the U.S. Centers for Disease Control and Prevention recommends that you: recommends Drink 8 ounces (1 cup) of water every 15-20 minutes while working. Drinking water both before and after work can help prevent chronic dehydration.

You exercise often: If you don’t have an active job but you do get a lot of exercise — whether at the gym or through recreational activities — you also need more water than most people. Even if you don’t realize it, you lose a lot of fluids during physical activity (even in cold weather). Increase your water intake to account for your activity (especially while traveling).

You live in a warm climate: Hot weather means more sweating and it is important to replace lost fluids. Dryness exacerbates fluid loss in hot weather — people in desert climates may need more water than people in tropical climates.

You are pregnant or breastfeeding: Pregnant people more water needed to promote better circulation, increased calorie intake and other physiological processes to support their baby’s growth. Breastfeeding people need extra water to support of breast milk production.

Several rules of thumb for hydration

Different people follow different hydration rules. These four general guidelines can help you stay hydrated, no matter what your lifestyle.

Drink when you are thirsty: There is some controversy surrounding this method. Some health professionals say that you shouldn’t make hydration too complicated and your body tells you when it needs water. Others say wait until you are thirsty waiting too long — that you are already dehydrated when you are thirsty. Some people seem to have stronger thirst mechanisms than others, so this method may or may not work for you.

Drink a glass before and between meals: This isn’t bad advice. Structuring your water intake around a ritual like mealtime can help ingrain hydration as a habit. Your total water intake will vary depending on how many meals you eat. If you eat three meals, this rule would have you drinking five glasses of water, which may not be enough (unless they’re large glasses). If you don’t have a consistent eating pattern, this rule probably won’t work for you.

Drink eight glasses a day: Again, one-size-fits-all health advice rarely works for everyone. If you feel adequately hydrated with 64 ounces of water per day, that’s great. If you feel overly hydrated (clear urine and very frequent urination), cut back a bit. If you feel dehydrated (dark urine, headaches, infrequent urination), eight glasses may not be enough for you.

Drink half your body weight in ounces: This is a simple guideline that is easy to remember and usually easy to achieve. If you weigh 150 pounds, try to drink 75 ounces of water every day. This is the only rule of thumb that takes into account different body sizes, but it does not take into account thirst, climate, activity level, or other factors.

Experiment with hydration techniques to find what works for you. As long as you don’t suffer from chronic fatigue, headaches, or other signs of dehydrationthen you’re probably doing pretty well. As a sort of emergency solution, you can always determine if you’re under- or over-hydrated based on the color of your urine.