Safe To Drink! Water is essential to your survival, you will live for a relatively long period without food but regardless of the weather conditions prevailing you will survive only a few days at most without access to water. In desert conditions you will be lucky to last out the day, loss of as little as 5% of your body's fluids can result in death. Even if you have a ready supply of water you may still have problems, is it safe to drink? contamination in water can lead to all sorts of complications, including vomiting and diarrhoea which will speed up fluid loss. Contaminants. There are two broad categories of contaminant found in naturally occuring water, chemical and biological. Chemical contamination is mostly caused by man as overspills from industry or agriculture but naturally occuring minerals can be poisonous also e.g. Arsenic. The biological category is more wide ranging, contamination can result from animal or human fecal matter getting into the watercourse or from waterborne diseases e.g. Giardia or Amoebic Dysentery. A third cause is contamination as an act of war or sabotage, unprotected water supplies are prone to poisoning in time of war, it may be by enemy action or as a result of Nuclear or Chemical combat in the water catchment area such contamination is virtually irreversable and is really beyond the scope of this article, the only sure method of obtaining pure water is to have your own sure supply from a protected source. Purification. These are your options:- Remove the pollutant from the water Remove the water from the pollutants Neutralise or destroy the pollutant. There are methods to affect these goals:- Heat treatment Filtering Chemical treatment HEAT TREATMENT Heat treatment generally means boiling the water for at least 10 minutes, this will generally kill waterborne diseases, but won't do anything about chemical contamination and may actually concentrate the poisons. A much more effective method of heat treatment is to use distillation, this involves boiling the water away to steam and then condensing the vapour, it leaves behind any solids, kills bacteria and gets rid of some chemical pollutants. Distillation will also produce drinking water from urine & sea water. To distill water boil it in a covered container, with some form of tubing leading from it to another cooller container where it will condense again into drinkable fluid. One possible source of tubing is the frame of a rucksack. Where conditions allow you can use a solar still, dig a hole about 3' acros and 1.5' deep place a container in the centre to collect liquid, then cover the hole with a sheet of plastic weighted in the middle with a small stone. The sun will heat the air below the plastic quicker than the outside air, causing vapour to condense on the sheet and run down into your container, if feasible use a piece of tubing, bamboo, reed or rucksack frame to draw off the liquid without disturbing the still. FILTERING In its most basic form, the cloth bag or sock filled with charcoal through which water is poured, filtering will remove debris and sand, silt or mud from water, while some commercial filters claim to remove everything down to almost viral level. I recommend that all filtered water also be boiled or chemically treated to remove any possible residual contamination. The combination of both treatments will almost guarantee safe drinking water. CHEMICAL TREATMENT The various iodine and chlorine based treatments on the market will destroy most waterborne bugs, with iodine being more effective in the removal of Giardia. Potassium Permanganate, used as a disinfectant generally can also be used to treat water, add until the water turns light pink and let stand for around an hour. chemical treatment does not of course remove any suspended matter, and to this end a simple filter can be rigged up. Water is a most necessary resource for your survival plan now and practice aquiring and purifying water or you may not live to face any more exotic dangers