Water makes up more than two-thirds of the weight of the human body. Without consuming water, humans would die in a few days. All the cells and organs need water to function.

Water serves as a lubricant. It makes up saliva and the fluids surrounding the joints. Water regulates the body temperature through perspiration. It also helps prevent and relieve constipation by moving food through the intestines.

You get some of the water in your body through the foods you eat. Some of the water is made during the process of metabolism.

You also get water through liquid foods and beverages, such as soup, milk, tea, coffee, soda, drinking water, and juices. Alcohol does not add to the body's water because it is a diuretic. It causes the body to release water.

If you do not get enough water each day, the body fluids will be out of balance, causing dehydration. When dehydration is severe, it can be life threatening.

The Dietary Reference Intake for water is between 91 and 125 fluid ounces (2.7 to 3.7 liters) of water per day for adults.

However, individual needs will depend on your sex, weight, age, and activity level, as well as any medical conditions you may have. Keep in mind that this is the total amount you get from both food and beverages every day. There is no specific recommendation for how much water you should drink.

If you drink fluids when you feel thirsty and have beverages with meals, you should get enough water to keep you hydrated. Try to choose water over sweetened drinks. These beverages can cause you to take in too many calories.

As you get older your thirst may change. It is always important to take in fluids throughout the day. If you are concerned you may not be consuming enough water have a conversation with your health care provider.

Diet - water; H₂O

Institute of Medicine. Dietary Reference Intakes for water, potassium, sodium, chloride, and sulfate (2005). National Academies Press. nap.nationalacademies.org/read/10925/chapter/2#13. Accessed October 4, 2023.

Ramu A, Neild P. Diet and nutrition. In: Naish J, Court DS, eds. Medical Sciences. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 16.

Updated by: Stefania Manetti, RD/N, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 02/05/2025.