How Much Water Do You Really Need?

“Oh! And one more thing!” I was speaking to a potential nutritional client who had just gone on for five minutes about all the things she wouldn’t do. “I won’t drink water! I get all the fluid I need from the foods I eat, so don’t tell me to drink water.”

I am always amazed to learn how little water people actually drink on a daily basis. One of my standard questions during a nutritional consult is, “How many 20 ounce bottles of water would you say you go through in a day?” Typical responses include: “Maybe one,” “Maybe half of that,” or “Does diet soda count?” While it’s true many foods have a high water content, the likelihood of an individual meeting all her water requirements through the foods she ingests is very low. Especially a physically active individual.


Perhaps part of the reason people downplay the necessity of water is because they don’t see it as essential. Think about it: supplement stores are a dime a dozen and what is lining their shelves? VITAMINS! Tons of them! In a nutrition shop close to my home, one aisle alone is dedicated to the many faces of the B vitamin. There’s B-Complex, Biotin, Niacin, B-12, Folic Acid, Pantothenic Acid, and the list goes on! Variables include doses, forms (B-12 soft chews anyone?), and even flavors of the vitamin. The fact is, water is the most essential nutrient in our diet and without it, we would die within a couple of days.

60% of the average adult’s body weight is made up of water, and it serves many bodily functions. Some of these functions you may already be familiar with. Forming saliva, regulating our body temperature, and lubricating our joints are just a few examples. Water is critical for the maintenance of our blood volume. Water also maintains the integrity of the fluid composition both inside and outside our cells.  Because water plays such an important role in maintaining all our bodily functions, our bodies will work to make sure that it is in a constant state of fluid homeostasis.

Dehydration results when you begin to lose more water than you take in. In an attempt to replenish the lost water volume, your hypothalamus sends out a signal that initiates the thirst response. This signal is enough to encourage you to drink. If you chose to ignore this signal and refrain from drinking, the severity of dehydration symptoms will increase. Symptoms range from impaired physical performance, severe headache, irritability, dizziness, delirium, and possibly even death. (1)


So, just how much water do we need to ensure we are properly hydrated? The Average Intake (AI) for total water per day (including water from food and other beverages) is suggested to be 3.7 liters a day for men and 2.7 liters per day for women. (1) This is an average intake recommendation. This does not take into consideration the individual’s diet, activity level, body weight, or environmental factors. Perhaps a more accurate measure of fluid needs is presented by Keith Klein, CN, CCN. His formula for adequate water intake deals specifically with the water we need to ingest per day in the form of water.

For non-athletes, Keith suggests that the person take her body weight and multiply it by .55 to get her average water intake needs.  In my case, I would take 135 and multiply it by .55 to get 74.25, meaning I need to drink a minimum of 74 ¼ ounces of water per day as an inactive adult. Athletes, on the other hand, need to drink slightly over half their body weight in water. Keith suggests one multiply her body weight by .66 instead. (2) I am quite active throughout the day and participate in both resistance training and cardiovascular activities on a daily basis. I would then want to drink a minimum of 89 ounces of water.


If you’re not used to drinking water, you’re probably thinking to yourself, “Whoa! How am I supposed to down X amount of water in a day?” It’s a lot easier than you think to get your daily allowance of water. One suggestion is to begin hydrating the moment you wake up. I drink 20 ounces of water as I prepare and eat breakfast. What helps me make sure I finish it all is to “treat” myself with my cup of coffee only after my first 20 ounces is consumed. For those of you who are about to hit the gym or participate in an endurance sport, it is suggested that you drink 24 ounces of water at least two hours prior to your workout/event. Then, drink  an additional 8-16 ounces 30 minutes before you begin. (3)

For the techie, there are apps available which allow you to track the amount of water you’ve consumed. There is also an old-fashioned tracking method many people still use. Simply mark lines on a bottle with goal times written next to the lines. By doing so, you have a visual reminder to drink a certain amount of water by a certain time. This helps you not only consume the amounts you need, but it also helps assure you are spreading these amounts evenly throughout the day.


Shake things up by adding flavor packets. Crystal Light or True Lemon are sweetened with Stevia for those of you who shy away from aspartame.

Better yet, buy an infuser water bottle such as sold by ASOBU. Bottles such as these allow you to add fresh fruit into an infusion compartment. The juice from those fruits seeps into the water, adding a hint of flavor to the water. Try is with ice, room temperature, or even tepid.


Your need for water is of paramount importance, whether you consider yourself to be an athlete or not. Be sure to drink adequate amounts of it spread evenly throughout the day and by all means, do not wait until you feel thirsty to pick up a water bottle! Remember, by the time you feel thirsty, you’re already dehydrated! The next time you’re visiting your local supplement store perusing the aisles of vitamins and minerals, be sure to stop by the refrigeration section to pick up the nutrient your body craves the most — WATER!

1) Rolfes, Sharon; Pinna, Kathryn; and Whitney, Ellie. Understanding Normal and Clinical Nutrition: Tenth Ed. Australia: Cengage Learning 2015©. Chapter 12: Water and the Major Minerals: 367-401.
2) Klein, Keith; Labrada, Lee. Get Lean.
3) Ryan, Monique, MA, RD, CSSD, LDN. Sports Nutrition for the Endurance Athlete: 3rd ED. Velo Press: 2012.

About the Author: Elizabeth Anastasopoulos

Elizabeth Anastasopoulos is a NASM Certified Personal Trainer and has been training clients for over 8 years. What she loves most about her position as a trainer is the variety of people she is fortunate enough to train: from the young and conditioned, to the elderly who simply want to keep moving, to those who are seeking sports specific goals. Each person brings with her a unique goal and challenge, giving Elizabeth an opportunity to grow personally and professionally.

Elizabeth is also very passionate about nutrition and nutritional counseling, which was brought on by her time as a figure competitor in the OCB. After witnessing and experiencing first hand the repercussions of faulty nutritional advice, she set out on a mission to become more knowledgeable. She obtained her Fitness Nutrition Specialist certification from NASM, then moved on to earn her Diploma in Comprehensive Nutrition from Huntington University of Health Sciences. However, her best education has come from her friend and mentor, Keith Klein, CN CCN of the Institute of Eating Management in Houston, TX, and the co-founder (along side Lee Labrada) of the on-line coaching club, Lean Body Coaching.

She has the great privilege of working for Keith and Lee as one of their Lean Body Coaches, and has found the greatest satisfaction in helping clients reach their weight-loss goals utilizing healthy nutritional concepts and Relapse Prevention strategies. Still, her greatest joy is her family. She is a proud wife, as well as the mother of a 22 year-old daughter and of 12-year old twins. As a family, they enjoy multiple outdoor activities and traveling to various destinations. If you would like to know more about Elizabeth’s training services or about Lean Body Coaching, you can check her out at:

Disclaimer: This content is for informational purposes only and is not meant as medical advice, nor is it to diagnose or treat any medical condition. Please consult your physician before starting or changing your diet or exercise program. Any use of this information is at the sole discretion and responsibility of the user.