Since we previously went into ways and places to find and store water, the next logical step is how to make it useable. A lot of different bacterial and pathogens can exist in water that will need to be removed prior to consumption. Failure to do so can wreak havoc on bodily systems and cause extreme illness, escalating your situation quickly from bad to worse.
Depending on the methods available to you, filtering and purifying water may not be terribly hard. Since portable water filters are now available that seemingly effortlessly make even the funkiest water drinkable, you may be able to use only those to get a drink. However, if you do not have such an item, or if it becomes lost or broken, filtering and purifying water can become a lot more difficult.
In the absence of a filter, be it portable or otherwise, probably the easiest thing to use is purification tablets. These are small and easy to carry/store and come with instructions for use. Generally it will take one or two tablets to purify a quart of water.
If you have access to iodine, it can be used for purification as well. Simply add 20 drops to a gallon of water and let the mixture sit for 30 minutes prior to drinking. Since some people possess iodine allergies and too much iodine can be harmful, use this method cautiously and as infrequently as possible.
Boiling water is safe and non-toxic as it does not require chemicals, but heating water to a boil will take some work. You are going to have to create a heat source capable of heating the water to a boiling point of 212 degrees Fahrenheit. It is possible to heat water at low temperatures for a longer period of time, but that will eat away at precious fuel reserves that you may not have to waste.
If a water still is accessible to you, it can be used to purify water by bringing it to a boil, moving it through copper tubing, and then condensing it back to water. To use this process, you will still need a fuel source strong enough to generate enough heat for boiling. You will also need the materials to build a still as well as a set of instructions, all of which will need to be gathered before the day comes that you will need it.
Water can be pasteurized through the use of solar heat as well. Place water-filled containers in direct sunlight and allow to heat to 158 degrees Fahrenheit. Be careful when using plastic bottles, however, as they can leach chemicals into your drinking water when heated.
When water is stored in clear, plastic bottles, it can be purified with UV light. This works in bottles that are smaller than two liters and they must be exposed to direct sunlight for at least 6 hours. If the water is especially cloudy, you should up that exposure to a couple of days\' time.
Bleach can be added to water to make it safe for consumption at a ratio of eight drops per gallon. Be sure the bleach you are using is unscented at concentrated between 5.25 6%. Mix the bleach and water and stir or mix then allow it to rest for a half an hour while the bleach does its work. If the water is particularly dirty, it may be necessary to use your bleach amount to 16 drops per gallon. You should also remember that bleach loses potency as it is stored so fresh bleach is best for this purpose.
Something else to remember when filtering or purifying water is that the smell of the water itself cannot always be removed. The water can be made drinkable while still retaining an odor that offends your sense of smell. When desperate times call for desperate measures, however, it may be necessary to suck it up and do your best to avoid any unpleasant odors wafting up from your drinking water. Although it would be nice to have a filtration method that filtered out smells, even the most highly regarded systems do not boast such an ability.
Be sure to exercise caution at all times when filtering water. The water itself can harm you in some cases but if done improperly, so can the treatment. Take care of yourself as well as your drinking needs by learning how to practice these methods in advance and carrying that knowledge with you in your travels. Safe drinking, my friends.