Every function in your body takes place in water. It is the solvent that removes the nutrients, hormones, antibodies and oxygen through your blood stream and lymphetic system. Water is also necessary to move the waste out of your body. We lose one half cup to one cup a day from the soles of our feet. Another two to four cups are lost from breathing.
Perspiration accounts for another two cups.
Urine output decreases and becomes very concentrated when you don't take in enough water. Since there is no way for your body to store water, it sets up a priority system for the amount that has been made available by intake. When you are dehydrated, your body rations and recylces water. All water losing functions are reduced. Toxic waste are dumped into tissues, fat, joints and muscles instead being eliminated.