Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Bloodthirsty: One Nation Under Water
When Trey dies in a fire at Wolfinger Biomed, Virgil has reason to suspect that his brother was murdered. Having nothing left to live for, Virgil decides to investigate his brother's death, even if that means staying in New Orleans long enough to die in the coming hurricane. What he uncovers is an underground cabal of hemovores - "an organism that ingests blood as the main part of its diet." Unlike vampires, the hemovores in "Bloodthirsty" are not supernatural beings; they are humans with a mutated gene that controls longevity. Their bodies are in a constant state of repair, which deprives their cells of oxygen. In order to compensate for this loss, they must consume fresh (oxygenated) human blood daily or they will die.