How to Boil Water to Make It Safe to Drink

When you can’t trust the tap, or you’re drawing from a stream, pond or rain barrel, boiling is the best way to make water safe: it kills the bacteria, viruses and parasites that cause disease.

The method

1. Clear it first. If the water is cloudy, strain it through a clean cloth, paper towel or coffee filter, or let it stand so the sediment settles and pour off the clear water.
2. Boil it. Bring the water to a rolling boil for 1 minute. At elevations above 6,500 feet (about 2,000 m), boil for 3 minutes.
3. Cool it covered. Let it cool on its own, with a lid on.
4. Store it clean. Pour it into clean, sanitized containers with tight covers.

Boiled water tastes flat. Pouring it back and forth between two clean containers a few times puts some air back in and improves the taste.

What boiling cannot fix

Boiling kills germs. It does not remove fuel, toxic chemicals or radioactive material, and you cannot make that water safe by boiling or disinfecting it. If you suspect chemical contamination (flood water near a road or farm, an industrial spill), find another source such as stored or bottled water.

No fuel to spare?

Boiling takes a lot of fuel. When fuel is short, use chemical disinfection with bleach, or a filter followed by a disinfectant. Start with the clearest water you can find whichever method you use.