Another necessity when trying to survive in the wilderness is knowledge of what to eat and drink when in a disastrous situation. These pages will help equip you with some knowledge of edible plants and what ones to avoid. There is also a section that explains how to treat and purify water. When you are placed in wilderness conditions with out food or water, keep in mind that you can live up to several weeks without food, but only a couple of days without water. When food and water is short in supply, don't waste energy. Do only what is necessary and no more. Also try to keep warm because shivering uses up calories.