Hydration

The human body is composed of 60 to 70% of water, and individual cells
are 80% water.
An sedentary adult requires 2.5 liters of water per day in a normal
environment.
One hour of moderate cardiovascular exercise causes approximately 1
litre of water loss through expiration and perspiration.
Water serves an important role in the human body, it allows for the
efficient transportation and exchange of oxygen, hormones, chemicals
and nutrients throughout the body. Water, or hydration, allows the
body to regulate and normalise temperature, assists in digestion and
the elimination of toxins and waste matter, lubricates joints, and
serves to create necessary body fluids such as tears, saliva, mucus,
and those involved in sexual function and reproduction such as semen
and amniotic fluid.

Interesting facts related to dehydration:
75% of Canadians are chronically dehydrated.
37% of 'thirst' signals are mistaken for hunger.
In a University of Washington study, 100% of dieters found that one
glass of water stopped midnight hunger pangs.
Even mild dehydration causes the basal metabolic rate to drop 3%.
Dehydration is the #1 cause of daytime fatigue.
Studies have demonstrated that drinking 1.5 liters of water per day
reduced symptoms related to back pain in 80% of sufferers.
A 2% drop in hydration was found to cause faulty short-term memory,
difficulty in concentrating and trouble resolving basic math problems
in the majority of test subject.
Death occurs at a 10% drop in hydration.
Staying well hydrated (1.5 liters per day) reduced the risk of colon
cancer by 45% and bladder cancer by 50%.

First signs of dehydration: tiredness, irritability, headache, hunger,
difficulty to concentrate. Chronic dehydration can contribute to
depression, 'foggy-headedness', mood-swings, insomnia, chronic
digestive problems, a suppressed immune system, high-level toxicity
and serious related illnesses.