Purifying water by boiling is effective for killing microorganisms, including both bacteria and viruses. Water is heated over a fire or on an emergency stove until it boils, and it must be kept at the boiling point long enough to kill the microorganisms that would typically live at room temperature.

To use this method or purification, you must be able to build a fire and find a heat proof container to hold the water. If unable to find a container that can withstand fire, it is possible to use heated rock boiling .

If you live at sea level, the water should be maintained at boiling point for one (1) minute. If you live at a high altitude, boil the water for three (3) minutes. The temperature at which most organisms (not just bacteria or viruses) are killed is approximately 2120 F.

1. Fill a heat-proof container of water
2. Filter the water
3. Start a fire
4. Place a container with water over the fire
5. Bring water to a boil and boil 1-3 minutes or longer
6. Allow water to thoroughly cool before drinking

One of the drawbacks to boiling is that it does not remove many chemicals, minerals or heavy metals.