General Health Status
Illness, such as fever, diarrhea and vomiting, can cause you to lose additional fluids. In addition, taking certain medications -- especially diuretics -- can also exacerbate fluid loss. Being sick can limit the amount of time your body can function properly without replacing lost fluids. On the other hand, engaging in a great deal of physical activity or exercise, even walking long distances because of famine, can increase the amount of water you need to survive.