How Much Water Should You Drink?

Jason Price, MS, CSCS, ATC, CPT, USAW Club Coach

I often get asked the question about how much water one should drink over the course of the day.  Now, I have always been taught the 8 x 8 rule on how much water to drink a day.  Now the 8 x 8 rule is 8 glasses of 8 oz of water a day.  Now here is where the confusion begins is it 8 oz of water or 8 oz of fluid.  Also what about size? I weight 250 and my wife 130 should we drink the same 8 oz eight times a day?  Now add to the confusion with this question, “What if I am working out how much water should I have?” Well I have been taught that for every 15 minutes of exertion you should intake 8-10 oz of water or fluid.  Well again that may seem straight forward.  But, what if you are training at altitude, hot weather or indoors?  So, the goal of this article is to hopefully clear some of the confusion with a simple way to think about how much water you should drink over the course of a day.

First let’s look at what can affect our hydration level.  There are several things that can affect your hydration level and when your body is 60-70% water this becomes fairly important.  Think about it your body can go a long time without food and survive.  Go only a few days without water your dead!  Here is a partial list of what can affect hydration level:

So why is water so important and why should we pay attention closely to our intake?  Simple if you are a normal adult you are 60-70% water.  Being dehydrated by as little as 3% of body weight can cause a 10% strength loss and 8% speed loss (1).  Several authorities on weight control and fat loss have stated that water intake is the key to fat loss.  The reason being is that metabolizing fat needs water.  So if you are skipping the water because you don’t want to gain “water weight” your missing out.  One last thing is that when your body stores carbohydrate as fuel in the form of glycogen it stores it with molecules of water!  If you don’t have those molecules in your system guess what you aren’t storing fuel.  So, if you are trying to train for optimal performance hydration is vital.

This brings us to the question, “Just how much water should you drink during the day?”  There truly is no formula that one can use to ensure that they are taking in enough water.  But, there are several methods that one can do to significantly reduce their risk of being or becoming dehydrated.  First, use the body weight method to calculate how much water you should take in over the course of the day.  The body weight method is to take your body weight in pounds and drink a 1/2 ounce per pound up to 2/3 ounce per pound.  For example I weight 250 lbs, my low end would be 125 ounces and my high end would be 165 ounces.  I would then calculate how many ounces I should drink during my waking hours.  I am typically awake for 16 hours a day.  So I would divide 125 and 165 by 16 to get 7.8 and 10.3 ounces per hour.  Now I would not stick to the intervals so I would know if I drank between 8 and 10 ounces an hour while I am awake I would be fairly hydrated.  The second method to follow is the color of one’s urine.  Now this may sound disgusting but urine color is one of the best measures of how hydrated you are.  The best measure is to measure ones specific gravity of their urine but that would be highly undesirable by most people.  An example urine hydration chart is provided at this link.

So now that you have an idea of how much water you should drink get to it.  Figure out how to get hydrated and stay hydrated your body will thank you.  Remember if you are thirsty than you are already on your path to being dehydrated. 

1) www.exrx.net/nutrition/water.html

[Home]