Water drop on poolYour body loses water through normal bodily processes such as sweating and urination.  A person loses and therefore requires an average of 2 to 3 liters of water daily.  Environmental factors such as heat, cold, and altitude as well as your level of activity can cause your body to lose even more water.  In extreme climates the average person can lose between 2 and 4 liters of water per hour.  This water loss must be replaced in order to survive.


Dehydration results from an inadequate replacement of lost body fluids.  Consider the following:

5% water loss

  • Thirst
  • Irritability
  • Nausea
  • Weakness

10% water loss

  • Dizziness
  • Headache
  • Inability to walk
  • Tingling sensation in arms and legs

15% water loss

  • Dim vision
  • Painful urination
  • Swollen tongue
  • Deafness
  • Numbness in the skin

Greater than 15% water loss

  • Death

Signs of Dehydration and Replacement of Water Loss

There are signs you can look for that indicate a person is dehydrated.  The most common signs and symptoms of dehydration are:

  • Dark urine with foul odor
  • Low urine output
  • Dark, sunken eyes
  • Fatigue
  • Emotional instability
  • Loss of skin elasticity
  • Trench line down center of tongue

imageIt is important to replace lost water as it is being lost.  In survival mode, trying to catch up on water loss is difficult to do and thirst is not a sign of how much water you need.  Be sure to drink small amounts of water at regular intervals to prevent dehydration.  If the environment or level of activity (physical or mental) is higher than normal then you should increase your water intake.

You can also regulate water loss through by allowing plenty of rest after physical activity and alternating between work and rest.  The objective is to limit the amount of sweat produced but not limiting the amount or frequency of water intake.  If you have no water, your priority must be to limit sweating by limiting activity or by initiating activity during nighttime hours when the weather is cooler.

Other factors

imageIf food intake is low, your water intake should be increased since much of our water intake comes from the foods that we ingest.  When food is scarce, water intake should be increased to 6 to 8 liters of water per day.

Remember that when your body loses water is also loses important electrolytes.  Carbohydrates or electrolyte supplements can be ingested to counter the loss.

Water is critical to the proper digestion of food.  If you have no water, do not eat food.  Eating food without drinking water can accelerate the dehydration process.

Otherwise, overhydration, which can cause low serum sodium levels resulting in cerebral and pulmonary edema or death, can occur. Overhydration can occur if water intake exceeds 1.5 quarts per hour.