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Tom Brady #12 of the New England Patriots sits on the sidelines late in the fourth quarter during the game against the Kansas City Chiefs at Arrowhead Stadium on September 29, 2014 in Kansas City, Missouri.
- There are lots of myths about how much water you need to drink. Some think eight glasses a day, others half their body weight in ounces.
- Water needs change depending on your activity level, your health, and the surrounding environment. Plus, you get hydration from other food and drink.
- Just drink when you're thirsty.
You should drink at least eight glasses of water a day, many of us were told as kids. The modern version of this is an astonishingly specific bit of advice from New England Patriots quarterback Tom Brady, who advises that people drink "at least one-half of your body weight in ounces of water every day."
This advice is wrong.
This shouldn't be a surprise - well-known "facts" about health often turn out to be false and Brady is full of misinformation when it comes to the
But the reality is even more simple. You should drink enough water so that you're not thirsty.
Specific numbers and goals don't make a lot of sense. That's because the amount of water needed to avoid dehydration varies depending on a huge number of factors. As the Mayo Clinic explains, you'll need more water if you're exercising, if it's hot or humid outside, if you're fighting off illness, or if you're pregnant or breast-feeding.
And we don't just get hydration from water. Any beverage will provide hydration (contrary to popular myth, you even get some hydration from a cup of coffee or a beer; it's only in larger quantities of caffeine or alcohol that beverages like this become more dehydrating than hydrating). Plenty of foods provide hydration as well, especially fruits and vegetables.
If you're trying to follow arbitrary guidelines or chug as much water as possible, you can actually drink too much water. That puts you at risk for hyponatremia, which is a rare but potentially fatal condition that occurs when you don't have enough sodium in your blood. (Athletes trying to maintain hydration levels during endurance sports have the greatest risk for this condition.)
There are older adults who may not notice thirst cues telling them they need to drink, registered dietitian Sharon Palmer told Insider. Those adults can just take a cue from their urine color. If your urine is a pale yellow, you're getting plenty of fluids, according to the Mayo Clinic.
But in general, just drink when you're thirsty and you'll be fine.