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  • Writer's pictureDr. Hansra

How much water you need to drink to optimize your health and optimize performance?

Updated: Feb 4, 2023

Why is water important?

Water is vital to life and humans need adequate water to perform a wide variety of essential bodily functions (1). Without water intake, humans can only live a few days (2). Did you know that adults are made of about 55-60% water by weight (3,4). Up to 75% of American adults are chronically dehydrated (5). How much water we need varies based on individual variables such as age, health issues, environment, exercise patterns, diet, and other factors. Staying hydrated has significant impacts on your health so familiarize yourself with aspects of hydration to benefit your overall wellbeing.

So how much water per day do you need?

Daily water recommendations generally range from 2–2.7 L/day (up to 11.5 cups) for adult females and 2.5–3.7 L/day (up to 15.5 cups) for adult males (1,6). Many experts simply recommend eight 8 ounce glasses of water per day which comes out to be 2L of water per day (4). Therefore for adult males and females 2L should be the minimum daily water goal. The amount of water you need depends on the individual. If you live in a hot/warm climate or you spend much time outdoors where you lose water through perspiration you should drink more water. If you have a medical condition like fevers, infections, vomiting, or diarrhea you should drink more water. Also if you are very active and lose much water through perspiration then you should be drinking more water. Always consider your personal lifestyle when adjusting your water intake.

How do you know if you've drinking enough water? Do you know how to recognize dehydration?

Water is lost from the skin, lungs, gastrointestinal tract, and kidneys (6). Dehydration results when water losses from the body exceed water replacement (6). Our bodies have carefully regulated mechanisms to signal us to intake more fluids. When we need more water our body will tell us that we are thirsty (4). Using your urine color is a good indicator of hydration status (7). In general the darker your urine the more dehydrated you are and the lighter your urine the better so aim to have pale clear urine (4). Also if you feel dizzy when you stand up especially after a long work out at the gym or after a long run that could also be a sign of dehydration called orthostatic hypotension (8). If you feel dizzy regularly you should call your doctor as this may represent a more serious medical issue. Feeling hungry or getting cravings may actually be a sign that you are dehydrated (9). If you're not sure if you're eating out of hunger vs. eating out of thirst it may help to drink a glass or two of water and wait to find out if you were just thirsty or really hungry. Other symptoms of dehydration include fatigue, headaches, and dry skin (10). Also, you can drink too much water so ensure you don't go overboard and drink too much as being overhydrated can lead to a variety of health consequences as well. If your urine is completely clear after drinking too much water then you might be overhydrated so you can back off.

What are the health benefits of hydration?

There is an abundance of data showing that maintenance of a good hydration status is good for your health. Being overhydrated does not appear to benefit your health but rather staying well hydrated is key for human health. Studies show that being well hydrated:

1) maintains good brain function (11-16)

2) helps avoid constipation (2, 4, 17)

3) helps to optimize physical performance (2, 4, 18)

4) facilitates weight loss (4,19-22)

5) maintains kidney health (2, 4, 23, 24)

6) helps keep skin hydrated (4, 25)

Water rich foods

Did you know that water also comes from food? It is estimated that about 20% of our daily water from from food (2). Try to incorporate water rich foods to meet your hydrations goals. In general these include fruits and vegetable that also have a slew of other health benefits. Here are a few examples:

90-99% water content: Fat-free milk, cantaloupe, strawberries, watermelon, lettuce, cabbage, celery, spinach, pickles, squash (2, 26).

80-89% water content: Fruit juice, yogurt, apples, grapes, oranges, carrots, broccoli (cooked), pears, pineapple (2, 26).

70-79% water content: Bananas, avocados, cottage cheese, ricotta cheese, potato (baked), corn (cooked), shrimp (2, 26).

The bottom line: Tips on staying hydrated.

1. Think of drinking water as medicine rather than for pleasure. I always tell patients that getting enough water is like putting enough oil in the engine to ensure your car runs smooth.

2. Aim for a minimum of 2 liters of water per day = 8 x 8 oz. glasses

3. Get a water bottle and fill it up with 2L of water. Think of this as a medicine bottle and make sure you take your daily dose.

4. Start your day by drinking a large volume of water to get your system going. Also drinking earlier in the day rather than later in the evening will help you avoid frequent nighttime bathroom trips.

5. If you work up regularly weigh your self before and after your workout and the difference in weight is water loss. You only have to do this a few times to gauge how much you need to replenish post work outs.

6. Use indicators of hydration and listen to your body: thirst, urine color, energy levels, other symptoms.

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1. European Food Safety Authority (EFSA) Panel on Dietetic Products Nutrition and Allergies (NDA) Scientific Opinion on Dietary Reference Values for water. EFSA J. 2010;8:1459–1507.

2. Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev. 2010 Aug;68(8):439-58.

3. Nicolaidis S. Physiology of thirst. In: Arnaud MJ, editor. Hydration Throughout Life. Montrouge: John Libbey Eurotext; 1998. p. 247.

4. Nutrition. How Much Water Should You Drink Per Day? ( Accessed April 5, 2021.

5. Taylor K, Jones EB. Adult Dehydration. [Updated 2020 Apr 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:

6. Food and Nutrition Board, Institute of Medicine (IOM) Panel on Dietary Reference Intakes for Electrolytes and Water . Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academy of Sciences Press; Washington, DC, USA: 2005.

7. Kostelnik SB, Davy KP, Hedrick VE, Thomas DT, Davy BM. The Validity of Urine Color as a Hydration Biomarker within the General Adult Population and Athletes: A Systematic Review. J Am Coll Nutr. 2021 Feb;40(2):172-179.

8. Lanier JB, Mote MB, Clay EC. Evaluation and management of orthostatic hypotension. Am Fam Physician. 2011 Sep 1;84(5):527-36.

9. 14 Reasons why you're always hungry. 14 Reasons Why You're Always Hungry ( Accessed April 6, 2021.

10. Shaheen NA, Alqahtani AA, Assiri H, Alkhodair R, Hussein MA. Public knowledge of dehydration and fluid intake practices: variation by participants' characteristics. BMC Public Health. 2018;18(1):1346.

11. Armstrong LE, Ganio MS, Casa DJ, Lee EC, McDermott BP, Klau JF, Jimenez L, Le Bellego L, Chevillotte E, Lieberman HR. Mild dehydration affects mood in healthy young women. J Nutr. 2012 Feb;142(2):382-8.

12. Zhang N, Du SM, Zhang JF, Ma GS. Effects of Dehydration and Rehydration on Cognitive Performance and Mood among Male College Students in Cangzhou, China: A Self-Controlled Trial. International Journal of Environmental Research and Public Health. 2019; 16(11):1891.

13. Cian C, Barraud PA, Melin B, Raphel C. Effects of fluid ingestion on cognitive function after heat stress or exercise-induced dehydration. Int J Psychophysiol. 2001;42:243–251.

14. Cian C, Koulmann PA, Barraud PA, Raphel C, Jimenez C, Melin B. Influence of variations of body hydration on cognitive performance. J Psychophysiol. 2000;14:29–36. 15. Gopinathan PM, Pichan G, Sharma VM. Role of dehydration in heat stress-induced variations in mental performance. Arch Environ Health. 1988;43:15–17.

15. D’Anci KE, Vibhakar A, Kanter JH, Mahoney CR, Taylor HA. Voluntary dehydration and cognitive performance in trained college athletes. Percept Mot Skills. 2009;109:251–269.

16. Suhr JA, Hall J, Patterson SM, Niinisto RT. The relation of hydration status to cognitive performance in healthy older adults. Int J Psychophysiol. 2004;53:121–125.

17. Arnaud MJ. Mild dehydration: a risk factor of constipation? Eur J Clin Nutr. 2003;57:S88–S95.

18. Goulet, Eric D.B., Mélançon, Michel O., Lafrenière, David, Paquin, Jasmine, Maltais, Mathieu, Morais, José A. Impact of Mild Hypohydration on Muscle Endurance, Power, and Strength in Healthy, Active Older Men, Journal of Strength and Conditioning Research: December 2018 - Volume 32 - Issue 12 - p 3405-3415.

19. Thornton SN. Increased Hydration Can Be Associated with Weight Loss. Front Nutr. 2016;3:18. Published 2016 Jun 10.

20. Jeong JN. Effect of Pre-meal Water Consumption on Energy Intake and Satiety in Non-obese Young Adults. Clin Nutr Res. 2018;7(4):291-296.

21. Dennis EA, Dengo AL, Comber DL, Flack KD, Savla J, Davy KP, Davy BM. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010 Feb;18(2):300-7.

22. Corney RA, Sunderland C, James LJ. Immediate pre-meal water ingestion decreases voluntary food intake in lean young males. Eur J Nutr. 2016 Mar;55(2):815-819.

23. Hooton TM, Vecchio M, Iroz A, et al. Effect of Increased Daily Water Intake in Premenopausal Women With Recurrent Urinary Tract Infections: A Randomized Clinical Trial. JAMA Intern Med. 2018;178(11):1509-1515.

24. Fink HA, Akornor JW, Garimella PS, MacDonald R, Cutting A, Rutks IR, Monga M, Wilt TJ. Diet, fluid, or supplements for secondary prevention of nephrolithiasis: a systematic review and meta-analysis of randomized trials. Eur Urol. 2009 Jul;56(1):72-80.

25. Palma L, Marques LT, Bujan J, Rodrigues LM. Dietary water affects human skin hydration and biomechanics. Clin Cosmet Investig Dermatol. 2015;8:413-421. Published 2015 Aug 3.

26. Altman P. Blood and Other Body Fluids. Washington DC: Federation of American Societies for Experimental Biology; 1961.


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1 Comment

Amrita Hansra
Amrita Hansra
Jul 11, 2021

Very detailed information which makes us more motivated to follow your advice as we can clearly see and understand all the benefits of hydrating our bodies. Thank you for this thorough post .

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