Water please!

Ever wondered how much water your body requires on a daily basis? What if you’re active and you workout like a beast?

In a normal environment (what we call room temperature), a sedentary adult requires on average 2.5 liters of water every day. Now, don’t start adding up how many glasses of water you would need since your water intake doesn’t only come from liquids. In fact, we drink (1200 ml) and eat (1000 ml) almost the same amount of water each day. Surprisingly, our body also produces water (350 ml) through the metabolic breakdown of different nutrients.



Yeah, my Photoshop skills aren’t that good.


If you were still looking for a clear-cut answer to the age-old question “how many glasses of water do I need to drink in a day?”, well here it is.

*Drumroll*…However many glasses it takes to equate 1.2 liters.

But that’s only if you’re sedentary and you live in a place where temperature doesn’t rise too much. If you become more active (ex: exercise, walking, active type of work) or the temperature of the environment in which you exercise increases, your total water requirement could rise from 2.5 L to 10 L a day!


So how exactly do I stay properly hydrated? It really comes down to the intensity/length of your workout and the temperature of where you’re exercising.

For your average (moderate intensity) workout at a temperature of around 26 degrees Celsius (80 F), you’re going to lose between 500 ml to 1 L per hour. Obviously, the harder you train and the hotter the temperature, the more water you’re going to lose per hour. Your goal should be to replenish water at the same rate that you’re losing it. Don’t worry, if you drink a bit more than you need, it can only help by increasing water absorption (by increasing gastric emptying).

With this in mind, your guidelines to stay hydrated through a regular workout should look like this.

  • Drink at least 500 ml per hour.
  • Drink at least every 15 minutes.
  • Use cold water since it increases the rate of absorption (again, gastric emptying).

If you’re on the other end of the spectrum and your training sessions are more intense, last longer than an hour and are done in a hot environment, take a look at these guidelines.

  • Drink extra water before working out in the heat. It will help your body regulate its temperature.
  • Consume at least 500 ml of water before sleeping the night before exercising in the heat.
  • Consume another 500 ml upon awakening.
  • Consume an additional 400 to 600 ml of cold water 20 minutes before exercise.
  • Drink about 250 ml every 15 minutes.
  • Add between 5% to 8% carbohydrate to facilitate absorption (5-8 grams per 100 ml)
  • Consider adding 1/3 tsp of salt per liter.
  • Don’t add protein to your beverage if you are training at a higher intensity and/or in a hot environment. Your body requires more water to process those proteins. Keep them for after your workout.
  • When you’re done, drinking a 250 ml glass of orange or tomato juice is enough to replace the calcium, potassium, and magnesium lost in 3 L (7 lb) of sweat.


I hope these guidelines will help you stay hydrated through your training sessions or even your competitions.

Raphael Hart

M.Sc. Kinesiology and Ph.D student in biological sciences at Université du Québec à Montréal.

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