How to Make Water Safe to Drink in an Emergency

Always follow your local water utility or health department. If they issue a boil-water advisory, do what they say. These are the general methods the CDC describes:

Boiling (best for germs)

Bring clear water to a rolling boil for 1 minute (3 minutes above 6,500 ft). If cloudy, let it settle and filter through a clean cloth or coffee filter first. Let cool and store in clean containers.

Disinfecting with bleach

Use regular, unscented household bleach (check the label for the concentration). For 6% or 8.25% bleach, the CDC's table is roughly 8 drops (about 1/8 teaspoon) per gallon of clear water; double for cloudy water. Stir and wait 30 minutes. It should have a slight chlorine smell. Check the current CDC table for your bleach's strength.

Filters

Portable filters vary a lot. Look for ones tested to NSF/ANSI standards and read what they remove: many filters do not remove viruses or chemicals. Boiling or disinfecting after filtering adds protection.

What these won't fix

Boiling and bleach do not remove chemical contamination, fuel, or heavy metals. If you suspect chemical contamination, use a different water source.

Sources: Ready.gov (Water), CDC (Emergency water supply; making water safe). Last reviewed Oct 2026.