Our bodies receive hydration from both food (about 20%) and drinking fluids about (80%) and women should consume about 91 ounces total and men about 125 ounces total.
Since drinking fluids is more easily measured than the intake of water-rich foods, it is the most important factor for achieving proper hydration.
Water comprises 60% of our body weight and allows proper performance both mentally and physically. Even mild dehydration is a physical stressor and makes concentration difficult.
There are variables to these water content guidelines in that someone with more lean muscle mass will need more hydration than someone with more fat cells since muscle cells contain more water than fat cells.
All fluids hydrate, including tea and coffee, except for Alcohol which actually draws out other fluids from the body and should be avoided. Too much water is dangerous and overhydration leads to dangerous low-sodium levels in the bloodstream.
Maintaining proper hydration is best achieved by meeting the recommended number of ounces per day in combination with using thirst as a guide and looking for a pale, yellow urine color.