Knowledge of water and the process of water purification has enabled several delegates to operate in a Hostile Environment.

Planet Earth comprises 29% of landmass and 71% of water.  Interestingly, this same ratio exists in the human body which consists of 29% of tissue and body mass and 71% of water.  Whether this ratio is a result of intelligent design or divine intervention is not known, but the reality is that the body requires more water than food in order to survive.

According to the “Rule of Three”, we can survive without air for three minutes; without water for three days; and without food for three weeks.  The “Rule of Three” is simply an indication to help us with our survival priorities. However it also reminds us of certain dangers regarding dehydration and the need for proper water processing in order to survive in a hostile environment.

Before assessing various water purification processes, it is important to understand a critical distinction between water supply and evaporation control.  The human body uses water not only to maintain consciousness and brain functioning, but also to enable the free flow of blood, the purification of organs and as a general means of preventing dehydration and subsequent death.

Yet, in a hostile environment where water is in short supply, experience has shown that it is better to reduce your body’s need for water rather than to ration water.  A lack of water in your body from perspiration, transpiration from exercise, skin drying out in the sun and moisture from your lungs will result in dehydration.

You can reduce your body’s need for water by resting in shade during the day, working at night, restricting exhaling, sucking on a pebble or button and keeping cool.  In this way, you only need replenish what is lost by sweating, exhalation and evaporation.  Drink water based on your bodily needs, rather than attempting to consume the minimum recommended amount of two litres per day.  Indeed, your search for water in a dry environment might cause you to lose more moisture than can be replaced by the water you find.

When you do find water, you need to make it safe to drink.  This process of water purification involves filtering and then purifying or distilling.  The alternative is to boil water for a minute after you have filtered out the larger particles.  But, although simple and effective against natural organisms, boiling will not remove chemical pollution or hydrocarbons.

One method of filtering dirty water is through sand.  Although soil is a good filter for sediment and other particles, it is not a guarantee for filtering the bacteria and deadly microbes that could live in the water source.

A water filter can be made from a plastic bottle cut in half and inverted. The bottom half should be punctured and acts as the water reservoir.  The cone is then filled with layers of sand, charcoal, grass and small stones.  The grass and sand helps to trap suspended particles and the charcoal helps remove many bacteria.  Remember though, you will have to pass the water through the filter several times – the bigger the filter and the more layers you have, the better.

Often, the water will appear dark, as it passes through the filter, and this could be because the water needs to be filtered repeatedly or there this tannin present.

Alternatively dig a hole about a metre from a water source, e.g. a pond, lake, river or the sea.  Allow the hole to fill with seepage water which will be relatively pure but will still need to be purified.

You can place impure water into a solar still and allow it to evaporate.

A common concern is whether your thirst can be quenched by drinking seawater, if you happened to be stranded on a desert island or along a shore line.  Many myths exist regarding drinking seawater with stories of thirst-crazed sailors, jumping into the sea, or killing themselves slowly by drinking ever increasing quantities of seawater.  Generally, it is not advisable to drink seawater because your kidneys cannot handle the processing of the high concentration of salt and other minerals in seawater.  Most survival guides empathize that drinking any seawater at any time, will kill you.

Rather, survival thinking suggests extracting potable water from seawater, either by capturing steam in a t-shirt or using a still.  Several other methods of converting seawater to drinking water are taught on our HEAT courses, as the same rules for water purification exist for seawater, as they do for contaminated water.

Yet, based on the experience of Thor Heyerdahl’s Kon-Tiki expeditions in the South Pacific, a little seawater added to drinking water was not only very refreshing but also extended the water supply on board the raft.  As in many survival scenarios, sometimes practical experience outweighs common thinking.  As such, we recommend that survivors in a hostile environment do not drink seawater on its own but, depending on the circumstances and security of supply, could mix a little seawater into drinking water, if both are fresh.

There are other practical measures to collect water in a hostile environment and the techniques and resources required are taught during our HEAT courses.  This knowledge of water and the process of water purification has enabled several delegates to operate in a hostile environment, without rationing precious water supplies.