Water is an essential nutrient required to maintain homeostasis in our bodies.
A deficiency in water, called dehydration, leads to headaches, loss of appetite, confusion, unexplained tiredness, and even seizures. Excessive dehydration can even lead to death.
Conversely consuming too much water can lead to nausea, muscle cramps, vomiting, and in extreme cases, death.
The U.S. Reference Dietary Intake (RDI) of water is 3.7 liters (130oz) per day for men and 2.7 liters (95oz) for women. Though people who are active and under the sun may need up to 16 liters (565oz) per day.