Nutrition & Health Info Sheets for Consumers – Water

Nutrition & Health Info Sheets contain up-to-date information about nutrition, health, and food. They are provided in two different formats for consumer and professional users. These resources are produced by Dr. Rachel Scherr and her research staff. Produced by Saba Almassi, Xianyu Zhu, Eli Cruz, Britt Loofbourrow, PhD Candidate, Anna M. Jones, PhD, and Rachel E. Scherr, PhD.

What is the role of water in the body?

Most of the water in the body is found inside cells. In all of our cells, water plays a role in vital functions like transport, waste management, and energy metabolism [1]. In addition, water is also important for maintaining body temperature. Water can also dilute harmful substances in the body and help us dispose of them in urine [1].

What are the recommendations for water intake?

Water intake differs from person to person, and even from day to day [2,3]. It is recommended that healthy adults consume 8-11 cups per day [4,5], and the water from foods and other beverages count towards this total [5]. Daily water recommendations can vary due to many factors [3]. Those who perform intense exercise may have greater water needs, due to water losses from sweating. Elderly people may need more water, as older age increases the risk of dehydration [6]. Young children may also need more water, especially during play and warm weather [7,8].

What is dehydration and how is it prevented?

Dehydration can occur when fluid losses are greater than fluid intake. When the body doesn’t have enough water, a hormonal response causes a person to feel thirsty and decreases the amount of water they lose through urine [9]. This response ends when the amount of water in the body returns to normal [10]. If the amount of water does not return to normal, dehydration can occur. Symptoms can range from moderate to severe, and may include the following [11]:

  • Excessive thirst
  • Fatigue
  • Muscle weakness
  • Headache
  • Dizziness
  • Dry mouth, lips and skin
  • No urination or a small amount of dark yellow urine
  • Lightheadedness
  • Increased body temperature
  • Nausea
  • Constipation
  • Labored breathing

Can too much water be harmful?

Drinking large amounts of water can be harmful in some situations. Normally, the kidneys are able to handle excess water by increasing urination. Rare cases of acute water toxicity and deaths have been reported [12], and all cases were related to drinking large amounts of water in a short period of time. Excess water can dilute vital minerals in the body, like sodium (which is called hyponatremia) [12], and can occur in athletes after drinking a lot of water without sodium. This can lead to nausea, vomiting, fatigue, and impaired performance. Very low blood sodium can lead to headaches, seizures, and/or a coma [13,14]. The American College of Sports Medicine suggests drinking beverages that contain sugar and electrolytes during endurance events [15].

Is there a difference between bottled and tap water?

In general, bottled and tap water are similar. People have many reasons for choosing to drink one over the other. Reasons may include taste, odor and appearance differences, and mineral content [16]. Consumers may prefer bottled over tap water due to safety concerns. However, tap water is highly regulated by government agencies to ensure its safety [16-17, 19].

To ensure the safety of citizens from toxic levels of metal or microbes in water, Congress passed the Safe Drinking Water Act in 1974. This law states that water contaminants such as metals or microbial growth must be kept at safe levels. However, this law does not apply to bottled water companies or other private-use water sources [18].

Are there benefits or risks associated with sports drinks, alkaline water, and raw water?

Sports drinks, like Gatorade®, have become popular recently, and the 2010 National Youth Physical Activity and Nutrition survey tells us that 16% of students drank more than 1 sports drinks per day [20]. Additionally, children who are not physically active were more likely to drink sports drinks. The American Academy of Pediatrics recommends water over sports drinks because water does not have added sugar [20]. The Institute of Medicine found that there is not enough proof to support sport drinks as a better beverage option for athletes, compared to water [20].

Alkaline and untreated water (also known as “raw water”) are two other options that have been introduced by the water industry. Alkaline water (pH of 8.8) refers to water that is more basic. Its pH is higher than the pH (6.7-7.4) of regular tap/bottled water. A higher pH level may help with acid reflux or heartburn as part of low-acid diet [21]. Alkaline water is marketed as a way to support an ideal body pH, but these claims are not supported by scientific research [22].

Raw water is untreated and unmodified in any way before being sold [23, 24]. Since water safety laws do not apply to private water sellers, the EPA safety standards may not be followed. For this reason, raw water is not recommended for consumption. Risks of drinking raw water include exposure to parasites and bacteria, which can cause severe illness [25].


  1. Selway JG, Granner DK. Metabolism at a Glance. Malden, MA: Blackwell Publishing; 2014.
  2. Guelinckx I, Ferreira-Pêgo C, Moreno LA, et al. Intake of water and different beverages in adults across 13 countries. European J Nutr. 2015;54(S2):45-55. doi:10.1007/s00394-015-0952-8.
  3. Johnson E, Muñoz C, Jimenez L, et al. Hormonal and Thirst Modulated Maintenance of Fluid Balance in Young Women with Different Levels of Habitual Fluid Consumption. Nutrients. 2016;8(5):302. doi:10.3390/nu8050302.
  4. Scientific Opinion on Dietary Reference Values for Water. EFSA Journal. 2010;8(3). doi:10.2903/j.efsa.2010.1459.
  5. Institute of Medicine. 2005. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: The National Academies Press. https://doi.org/10.17226/10925.
  6. Drink Up: Dehydration is an Often Overlooked Health Risk for Seniors https://health.clevelandclinic.org/drink-up-dehydration-is-an-often-overlooked-health-risk-for-seniors/.
  7. Water: How Much Do Kids Need? Eat Right. Academy of Nutrition and Dietetics. https://www.eatright.org/fitness/sports-and-performance/hydrate-right/water-go-with-the-flow.
  8. Water and Healthier Drinks. Centers for Disease Control and Prevention. https://www.cdc.gov/healthywater/drinking/nutrition/index.html.
  9. Fitzsimons JT. Angiotensin, thirst, and sodium appetite. Physiol Rev. 1998 Jul;78(3):583-686. doi: 10.1152/physrev.1998.78.3.583. 
  10. Jain A. Body fluid composition. Pediatr Rev. 2015 Apr;36(4):141-50; quiz 151-2. doi: 10.1542/pir.36-4-141. 
  11. Fluid Needs. Home & Garden Information Center | Clemson University, South Carolina. https://hgic.clemson.edu/factsheet/9675/.
  12. Farrell DJ, Bower L. Fatal water intoxication. J Clin Pathol. 2003 Oct;56(10):803-4. doi: 10.1136/jcp.56.10.803-a. 
  13. Noakes TD. Water intoxication-considerations for patients, athletes and physicians. Pract. Gastroenterol. 2008 Sep;32:46-53.
  14. Hew-Butler T, Rosner MH, Fowkes-Godek S, Dugas JP, Hoffman MD, Lewis DP, Maughan RJ, Miller KC, Montain SJ, Rehrer NJ, Roberts WO, Rogers IR, Siegel AJ, Stuempfle KJ, Winger JM, Verbalis JG. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clin J Sport Med. 2015 Jul;25(4):303-20. doi: 10.1097/JSM.0000000000000221.
  15. American College of Sports Medicine, Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007 Feb;39(2):377-90. doi: 10.1249/mss.0b013e31802ca597.
  16. Saylor A, Prokopy LS, Amberg S. What's wrong with the tap? Examining perceptions of tap water and bottled water at Purdue University. Environ Manage. 2011 Sep;48(3):588-601. doi: 10.1007/s00267-011-9692-6. Epub 2011 Jun 4.
  17. Lead in Drinking Water in Schools and Childcare Facilities. EPA. https://www.epa.gov/dwreginfo/lead-drinking-water-schools-and-childcare-facilities.
  18. Olson ED, Poling D, Solomon G. Bottled Water: Pure Drink or Pure Hype? Attachment to the NRDC Citizen Petition to the US Food and Drug Administration for Improvements in FDA’s Bottled Water Program. February 1999:1-111. https://www.nrdc.org/sites/default/files/bottled-water-pure-drink-or-pure-hype-report.pdf.
  19. Understanding the Safe Drinking Water Act.; 2004. https://www.epa.gov/sites/default/files/2015-04/documents/epa816f04030.pdf.
  20. Committee on Nutrition and the Council on Sports Medicine and Fitness. Sports drinks and energy drinks for children and adolescents: are they appropriate? Pediatrics. 2011 Jun;127(6):1182-9. doi: 10.1542/peds.2011-0965. Epub 2011 May 29.
  21. Koufman JA, Johnston N. Potential benefits of pH 8.8 alkaline drinking water as an adjunct in the treatment of reflux disease. Ann Otol Rhinol Laryngol. 2012 Jul;121(7):431-4. doi: 10.1177/000348941212100702.
  22. Zeratsky KR. Alkaline water: Better than plain water? Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/nutrition-andhealthy-eating/expert-answers/alkaline-water/faq-20058029. Published February 8, 2018.
  23. Bowles N. Unfiltered Fervor: The Rush to Get Off the Water Grid. The New York Times. https://www.nytimes.com/2017/12/29/dining/raw-water-unfiltered.html. Published December 29, 2017.
  24. Kirby J. What to Know About the “Raw Water” Trend. Vox. https://www.vox.com/science-and-health/2018/1/4/16846048/rawwater-trend-silicon-valley. Published January 4, 2018.
  25. Mitchell, L. “Raw” Water Risks. University of Utah Health. https://healthcare.utah.edu/healthfeed/postings/2018/01/raw-water.php. Published January 4, 2018.

Inquiries regarding this publication may be directed to cns@ucdavis.edu. The information provided in this publication is intended for general consumer understanding, and is not intended to be used for medical diagnosis or treatment, or to substitute for professional medical advice.