Editor's note: this post originally appeared in May 2013 and has been updated and revamped for accuracy.
Are you drinking enough water? Of all the life sustaining substances on the planet, water is the one you don’t want to mess around with. While the human body can pull from tissue and fat stores to sustain life in the absence of food, a person will literally die without water in as little as three days.
Water is absolutely essential to healthy body function. Every system in your body depends on it, from your blood to your bones. It helps flush waste from your lymph system, gives cushion to joints and soft tissues, and greases the wheels in digestion.
If you’ve never paid much attention to your water intake, it might be time to start. Dehydration can occur quickly, and effect you in ways you wouldn’t expect. Fatigue, poor cognition, and irritability are just some symptoms that could sneak up on you in the absence of enough H2O.
But how much is enough? Science has suggested that 8 glasses of water a day is the magic number, but the truth is, it’s not as cut and dry as that. The simple answer is that there is no “perfect” amount that can be prescribed to encompass the entire population. How much water an individual needs is dependent on several factors, and cannot be generalized across the board.
Consider these factors when determining your fluid needs:
Have you been sick? Stomach bugs and fevers can exacerbate hydration issues. If you’re sick, or have been recently sick, pay extra attention to your water intake, and try to eat veggies and fruits, such as tomatoes and melon, that have a high water content.
Where do you live? People who live in Eureka, California won’t have nearly as much trouble staying hydrated as people who live in, say, Death Valley, where the temperature regularly climbs well above 100 degrees fahrenheit. Heat and wind speed surface evaporation, and as your body sweats to keep cool, you’ll lose valuable fluids.
It’s no secret that exercise makes you sweat, which can lead to dehydration. A good rule of thumb to follow is to rehydrate with 1/2 a cup of water for every 15 minutes of moderate exercise you perform, increasing to 1 cup for extra strenuous exercise.
This is a sneaky one. Protein requires more water to process than other macronutrients. Make sure that if you’re ingesting more protein than the recommended 0.8 g of protein per kilogram of body weight per day, you are offsetting that with additional water.
A safe place to start would be with your eight glasses a day, and watch how you feel from there. Be aware of your mood, energy levels, and thirst, and adjust water intake to account for your health, climate, activity level, and protein intake. Remember, your entire system depends on your hydration, and you’re the only one who can take the reigns.