How long must you boil water to purify it?

To effectively purify water through boiling, the general guideline is to boil it for at least 1 minute at altitudes below 6,500 feet. The key aspect is that boiling water kills most pathogens, including bacteria, viruses, and parasites, which makes it safe for consumption. Though the choice you selected states 15 seconds, which may seem sufficient in some casual contexts, the recommended practice for ensuring thorough purification at sea level is actually around 1 minute.

Boiling for an adequate duration ensures that the water reaches a temperature that neutralizes contaminants, particularly if there are higher altitudes involved where water boils at lower temperatures. Therefore, while shorter durations may remove most pathogens, to guarantee safe drinking water, a full minute of boiling is advisable, especially in uncertain conditions.