In a survival situation, clean drinking water is your most important resource. Depending on the environmental conditions and your physical activity, a person cannot safely go longer than a few days without water.
If you are embarking on a household preparedness effort, water needs to be at the top of your list. Plan for at least one gallon of water per person per day to satisfy drinking and food-preparation needs. Beyond that, additional water is needed for hygiene. If you can store purified or city-treated water in a cool dark area, that is an excellent start. Ideally, you want to use new water-storage containers or barrels that meet UN and FDA regulations. You should rotate/freshen your water storage every six months or so unless you treat that water with water preserver concentrate that can extend your shelf life to five years. (Household bleach is not a water preserver. In fact, bleach loses potency very quickly—any bleach that is beyond six months out of the factory is largely worthless for purification purposes.)
It’s good to have on hand several different capabilities for purifying water.
Boiling: The old standby and probably the best method is the ability to boil water. Boil for at least 10-15 minutes to kill most bacteria, parasites, and viruses. Allow to cool to room temperature.
Chemical disinfection: The next best option is to use a proper dosage of a commercially produced water purification tablet, such as Katadyn Micropur, Coghlan’s, or Potable-Aqua. Iodine products such as tincture of iodine or crystalline iodine are also effective. (Important: iodine can be lethal if used in quantities greater than recommended and iodine-treated water should not be used by pregnant women or consumed by anyone for more than a few weeks at a time.) Note that cryptosporidium and other parasites may not be killed using chemical disinfection methods. Be sure to follow directions for each product with measured water volumes.
Portable water filters: The thing to look for with water filters is the filter’s absolute pore size. Filters are designed to remove parasites (Giardia/Cryptosporidium) and have an "absolute” pore sizes of 0.1 to 1-micrometer (the smaller the pore size, the better). They will also remove most diarrhea-causing bacteria. Most portable water filters do not remove viruses so chemical disinfection is recommended after filtration.
Chlorine (NOT a good option): Chlorine has been thought by many to be a reliable way of treating water, but it is risky doing so, since chlorine degrades so quickly and loses its efficacy. Iodine or other stable water-treatment chemicals are more effective.
For more info on water treatment options, visit: