Boil water for 1 minute to kill pathogens. At high altitudes, boil for 3 minutes. This is the most reliable method for killing bacteria and viruses.
Boil water and collect the steam in a container. The condensed steam is pure water. This method removes salt and chemicals but requires energy and time.
Use a portable water filter with a pore size of 0.2 microns or smaller to remove bacteria and protozoa. Pre-filter cloudy water through a cloth before filtering. Filters do not remove viruses.
Use chlorine dioxide or iodine tablets according to package instructions. Allow the water to sit for the required time (usually 30 minutes) before drinking. This does not remove heavy metals or chemicals, only biological pathogens.
Fill clear plastic bottles with clear water and lay them in direct sunlight for 6 hours (or 2 days if cloudy). UV radiation kills pathogens. This method works best for clear water and does not remove chemicals.
Boiling water at a rolling boil for 1 minute (3 minutes at altitudes above 6,500 feet) kills bacteria, viruses, and parasites. This is the most reliable method when chemical purification is unavailable.
