Body Water, Defined

You are made up of mostly water, H2O! Water can be found inside your blood, your muscles, your fat, your organs, and every cell in your body.  Your blood makes up part of your total body water.  Water makes your body run smoothly.

Water Weight – your overall body weight can be 45-65% of total body water!
The percentage varies depending on age, gender, and fitness level.
~ WaterScienceSchool

The water in your body is either Estracellular or Intracellular Water:


Extracellular water (ECW) is located outside of your cells.  The water in your blood falls into this category.  Roughly 1/3 of your body water is attributed to ECW, and this water is found in your interstitial fluid, transcellular fluid, and blood plasma. ECW is important because it helps control the movement of electrolytes, allows oxygen delivery to the cells, and clears waste from metabolic processes.


Intracellular water (ICW) is the water located inside your cells.  It composes 70% of the cytosol, which is a mix of water and other dissolved elements.  In healthy people, it makes up the other 2/3 of the water inside your body.

The ICW is the location of important cellular processes, and although it has many functions, a very important one is that it allows molecules to be transported to the different organelles inside the cell.  Essentially, the ICW picks up where the ECW left off by continuing the pathway for fuel to be transported to the cells.

Your Water Intake

Doctors and nutritionists around the world agree that drinking enough water every day is good for your overall health. Although no one can seem to agree on how much water is “enough”. The recommended amount varies based on age, sex, pregnancy, race, socioeconomic, and behavioral characteristics. It is critical to drink enough to prevent dehydration and overheating! It can help reduce inflammation and it can also be used to help manage body weight and even reduce caloric intake.

As with all things in Functional Medicine we believe each individual should have a unique H2O intake requirement. You should be assessed and monitored.

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U.S. Geological Survey article “The Water in You: Water and the Human Body” by WaterScienceSchool.