Many of us have wholeheartedly accepted the idea that we need to drink 8 eight ounce glasses of water per day for good health.  A good look at Chinese, Tibetan, Ayurvedic and Western medicine theories will all reveal this thought for just what it is – a myth.  For years we have also been told that drinking caffeinated beverages doesn’t count towards water intake because the caffeine acts as a diuretic, flushing water from our bodies.  Also not true.

When we consume food and beverages our bodies are smart enough to extract water molecules from what we eat and drink for use where needed and send the remainder out.  Obviously people suffering from some disorders like edema have bodies that are not regulating water correctly and may need to look more carefully at their fluid consumption and regulation with a doctor.

It appears that the 8 glasses of water per day recommendation came out of a 1945 report from the Food and Nutrition Board of the National Research Council which stated “A suitable allowance of water for adults is 2.5 liters daily in most instances.  An ordinary standard for diverse persons is 1 milliliter for each calorie of food.  Most of this quantity is contained in prepared foods.”  What seems to have gotten lost in time was that last sentence stating that most of the water needed is supplied by the food we eat.  Particularly today when we are recommending that people eat lots of fresh fruits and vegetables which contain a lot of water, most of our water needs should be supplied by the food we eat.

It is also possible to do harm by consuming too much water in a day.  From an Ayurvedic perspective consuming too much water can douse the digestive fire so it’s not hot enough to function effectively.  Chinese medicine also sees the consumption of too much fluid or foods of a damp nature as damaging to the spleen and stomach or earth elements which then adversely impacts digestion.  Ayurvedic, Chinese and Tibetan perspectives all advocate for consumption of fluids in moderation.  Also more attention is being paid today to a condition called exercise-associated hyponatremia (EAH) or water intoxication, in which the kidneys become overwhelmed by the large quantity of liquid it’s forced to process. The body’s naturally occurring sodium can’t keep up with the amount of water, leading to swelling in the cells and in severe cases, death.

A healthier guideline for how much water and other beverages we need to consume each day would be:

• Drink when your mouth or throat are dry and when you feel thirsty.
• Observe the color of your urine.  If it’s clear or very pale yellow like the color of straw you are well hydrated and do not need additional fluids.  If it’s darker yellow or brownish you are dehydrated and need to consume more liquids.
• Try to take in most of your liquids at either room temperature or slightly warm.  These are closer to the body’s normal temperature and don’t require the body to work harder to assimilate them.  The same temperature guideline is also appropriate for the food you eat; extremes of hot or cold food or drink are harder for the body to process.
• If you are in hot weather, sweating profusely from exercise, running a fever, losing fluids due to diarrhea or have a tendency to kidney stones then higher fluid consumption is recommended but within reason.

http://www.itmonline.org/arts/water.htm
http://www.webmd.com/fitness-exercise/water-intoxication