Well, if you happen to have this nifty survival guide lying around, you'll know that boiling water is the most effective way of getting rid of any nasty pathogens that might render your drinking experience, shall we say, "unpleasant." In fact, boiling water is a much better way of obtaining safe drinking water, even when compared to modern marvels like filtering devices or chemical treatments. Once you get your hands on a container to hold the water and, of course, a source of heat to boil it, you're ready to go. Or are you? The next important matter to consider is the appropriate water boiling time. Various numbers are often thrown around: 10 minutes, 5 minutes, 20 minutes or even 1 minute (which doesn't really work in principle), but there appears to be little consensus as to which is best.
According to the guide's author, however, each above quoted time is wrong. The right amount? Zero minutes. As he explains, heating the water to a temperature of approximately 165°F (74°C) and leaving it for half an hour should be enough to kill any pathogens that are present. You can also raise the temperature up to 185°F if you're in a hurry and leave the water for a few minutes, which should also be enough to destroy any pathogens. No need to up the temperature once you reach the boiling point at 100°C, at which point the pathogens should be gone.
The benefits are clear: you save fuel by not having to consume as much firewood (or whatever biomass source you may choose to use) and don't waste any precious water by letting part of it evaporate. Handy advice to have if you're ever in a tight spot (and want to remain sustainable).
UPDATE: Yes, as several clever readers have already pointed out, you'd need a third device in your toolkit (which we omitted) to make this advice applicable: namely a thermometer. Good luck getting stranded with all three, though.
Also, another reader has just posted a comment noting the information is, as she puts it, "dead wrong," and she recommends checking out the following website. After conducting our own bit of research, we did find out that bleach can be used to eliminate most pathogens in water (if boiling isn't practical), but that it should only be used if boiling water is not practical at all. The main point the guide's author was getting to is that you don't need to boil the water for very long: once you actually reach the boiling point, you should be able to let it cool and safely drink it.
Via ::Survival Topics: How Long Do You Need To Boil Water? (how-to guide)