The three basic necessities which sustain life are: 1. air, 2. water, and 3. food. The Rule of Threes states that a person can live for: three-minutes without air, three-days without water, and three-weeks without food.

Without water or any other fluids, a person will die in about three days.

Therefore, since water is one of life's most basic necessities, it is a subject we should not take for granted.