Survival guides · Water & Food

Purify Water by Boiling

WHEN TO USE THISThe most reliable way to make water safe. If you can heat it, you can drink it.

1. Clear it first

   • Use the cleanest water you can find. Running beats still.
   • Cloudy or full of bits? Pour it through a cloth, coffee filter or folded fabric.

2. Bring it to a rolling boil

   
   • Big bubbles breaking the surface, nonstop.
   • A simmer isn't enough.

3. Keep it boiling

   
   • 1 minute at a full rolling boil.
   • 3 minutes above 6,500 feet (2,000 m).
   Why

   Water boils at a lower temperature up high, so it needs longer to kill the same germs.

4. Cool and store

   • Let it cool on its own. No ice — it may be contaminated.
   • Clean containers with tight lids.
   • Tastes flat? Pour it back and forth between two clean containers.

Sources: CDC Water Disinfection Guidelines · EPA Emergency Disinfection of Drinking Water

General information to help in an emergency — not a substitute for training or professional care.