How to make questionable water safe to drink
Two reliable methods, in order of preference: heat, then plain bleach. The numbers below are EPA guidance.
Do this now
- Boiling is best: a rolling boil for 1 full minute (3 minutes above ~6,500 ft elevation). Let it cool.
- No way to boil? Use plain, unscented household bleach (5–9% sodium hypochlorite).
- 8 drops (⅛ teaspoon) per gallon of clear water. Double it — 16 drops — if the water is cloudy.
- Stir, then wait 30 minutes. A slight chlorine smell is right. None at all? Repeat the dose and wait 15 more minutes.
Before you treat it
If water is cloudy, let it settle and pour it through a clean cloth, paper towel, or coffee filter first. Disinfection works on clear water; particles shelter germs.
What bleach to use — and what to avoid
Plain liquid household bleach only: unscented, not color-safe, no added cleaners, and not expired (bleach loses strength within about a year). Scented and splashless varieties are not for drinking water.
How much water you actually need
Plan on one gallon per person per day — half for drinking, half for basic hygiene — and at least a three-day supply. Children, nursing mothers, sick people, and hot weather push the number up. Don't forget pets.
Know your hidden reserves: the water heater tank holds 30–50 gallons of usable water, and the toilet tank (not the bowl, and only if it has no drop-in cleaners) holds a few more.
Do not
- Don't use scented, splashless, or color-safe bleach — those are not for drinking water.
- Don't drink flood water, or water with fuel or chemical smells — bleach and boiling can't fix those.
- Don't skip the 30-minute wait after adding bleach.
- Don't ration water to the point of dehydration — find more water instead of drinking dangerously little.
Common questions
How many drops of bleach per gallon of water?
8 drops (about ⅛ teaspoon) of plain 5–9% unscented household bleach per gallon of clear water; 16 drops if cloudy. Stir and wait 30 minutes before drinking — EPA guidance.
How long should I boil water to purify it?
Bring it to a rolling boil for 1 full minute — 3 minutes at elevations above roughly 6,500 feet — then let it cool.
How much water should I store for emergencies?
One gallon per person per day, minimum three days. A family of four should store at least 12 gallons.
Sources — official guidance
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