Water is the most important food source of all. Without a constant supply of clean drinking water, a person can die of thirst within a few days. Extreme travelers regularly venture into regions where this supply is not reliably guaranteed. Emergencies or disasters can also cut people off from water sources. Johannes Vogel presents the topic in a way that enables everyone, whether trekking traveler, recreational hiker, or survivalist, to obtain drinkable water from nature. The reader will learn the essential techniques for accurately assessing found liquids and safely purifying them.