Water in Adverse Environments (Part 4 of 4)

Thanks again to  Pete Farmer for the following post.  Don’t forget to read the rest of the series Pete has so graciously shared.  (See http://armageddonmedicine.net/?cat=229)

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In the previous three installments of this series, we considered at length the chemical and physical properties of water, the human physiology of fluid balance, including recognizing and treating dehydration, and finding and treating water in adverse environments. To conclude the series, the following article will consider a few additional aspects of water and survival in adverse environments not previously covered, as well as tie up some loose ends. 

Animals as diagnostic indicators of water 

In part 3 of the series, we discussed finding water in the wilderness settings, specifically

using local terrain features and plant life as guides to lead you to water. However, an important facet of these techniques was omitted – animal life as a guide to finding a reliable water source. John Wiseman’s indispensable “SAS Survival Handbook” (Harper Collins, 2009) notes that local wildlife may be used as a diagnostic indicator of the presence/absence of water (p.42), but with the caveat that different varieties of wildlife do not necessarily indicate the same things regarding water. Most mammals require water at regular intervals, or at least at dawn or dusk; grazing animals generally congregate near and do not stray far from water. Game trails often converge downhill upon springs, watering holes, and the like. However, some species migrate seasonally to mate, or provide themselves with reliable food, water, and cover – and may thus be seen far from water at times.

Carnivores, which get much of their hydration from their prey, can go for long periods without water and are not reliable indicators of a nearby source (an exception is that they often track prey by hunting near watering holes). Birds are unreliable indicators of water, except for grain-eating species such as finches and pigeons, which do not stray far from water. When heading for water, they fly straight and low. Reptiles can go long periods without water, and are thus also unreliable indicators. Insects are usually good indicators, especially bees and ants. Bees generally go no further than four miles from their hives, and need a reliable source of water, as do ants. Flies generally go no further than 100 yards from water or a source of moisture. 

 Plants and animals as sources of water 

Wiseman notes that safe drinking water can be obtained from a variety of plant and animal species, depending on the local flora and fauna. SAS personnel are trained to operate in virtually every environment found on Earth, and are thus expected to improvise using whatever natural resources are on-hand. Parasitic plants of the tropics, such as members of the bromeliad family, are often cup-shaped and thus catch water. Bamboo can trap water in its hollow joints, which can be drained by cutting into the stalk. Some species of woody vines entrap water, though Wiseman cautions that some varieties have poisonous sap. Some types of palm trees contain a sugary fluid which is drinkable. Coconut milk is safe and nutritious – but avoid over-ripe coconuts, as their milk acts as a laxative. Desert plants and roots can yield moisture – Wiseman recommends having an experienced guide show you which ones are best to use. Some desert and dry-adapted plants, such as the famed saguaro cactus, produce liquid that looks safe but is poisonous; others such as the barrel cactus, yield watery sap and pulp laden with safe-to-drink water. The prickly pear cactus can also be harvested for its pulp and fruit. Again, knowledge of the local plant life is critical; forewarned is forearmed. 

Moving on to animal sources of moisture, Wiseman notes that most animal eyes contain fluid which can be consumed in an emergency. Fish, especially larger species, tend to accumulate a reservoir of fresh water alongside their spines; by carefully dressing the fish, this can be collected and consumed. Certain amphibians/frogs can be squeezed to collect water. 

The above methods for harvesting water are obviously a last resort, when more reliable methods are not possible. It should be stressed again that not all plants are safe sources of moisture. Many plants produce potent alkaloids or other poisons to ward off predators. In some plants, the leaves and stems are safe to consume, but the fruit is poisonous; in others, the opposite obtains. There is no substitute for knowledge of the local flora and fauna. 

Melting snow and ice for water

 Wiseman recommends melting ice rather than snow, if you have a choice, given that ice produces more volume of water with less heat. More densely-packed snow will yield more water than freshly fallen layers. 


Unless you are a seasoned field biologist, outdoorsman, or wilderness survival expert, who can rely upon years of accumulated experience, knowledge and training – you are probably operating at a knowledge deficit when  you find yourself in the wilderness. If you are caught in such circumstances by chance, you will have to rely on good judgment, resourcefulness and knowing your limitations to pull you through. However, if you plan to travel into the wilderness, it is essential that you do your homework beforehand in case you find yourself in dire straits unexpectedly. Mother nature can punish you when you least expect it. Do not be too proud to hire an experienced guide or other party with appropriate experience; such a person can mean the difference between walking out and being carried out. Know thoroughly the area and region in which you will be traveling, including the local flora and fauna. Plan thoroughly, equip yourself well, and notify others of your exact route, time and expected place of return, and other vital information, and things should turn out well. Happy travels… and don’t forget to bring plenty of water!

Coyright © 2011 Peter Farmer

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About Cynthia J. Koelker, MD

CYNTHIA J KOELKER , MD is a board-certified family physician with over twenty years of clinical experience. A member of American Mensa, Dr. Koelker holds degrees in biology, humanities, medicine, and music from M.I.T., Case Western Reserve University School of Medicine, and the University of Akron. She served in the National Health Service Corps to finance her medical education.
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