How many drops of bleach do you need to disinfect water?
For clear water, use 2 drops of plain, unscented household bleach (4–6% sodium hypochlorite) per liter, stir and wait 30 minutes; the water should smell slightly of chlorine. Double the dose for cloudy or very cold water. With 8% bleach, use 1–2 drops per liter. Always check the label and your local health authority's guidance.
Dosage per liter
| Concentration on the label | Clear water | Cloudy or cold water |
|---|---|---|
| 4–6% | 2 drops | 4 drops |
| 8% | 1–2 drops (about 1.5) | 3 drops |
- Stir and wait 30 minutes; the water should smell slightly of chlorine.
- Use only plain, unscented bleach — never scented, "color-safe" or gel bleach.
- Bleach does not remove chemicals, fuel or floodwater contamination and does not reliably kill some parasites. If you suspect that kind of contamination, don't drink the water.
Bleach strength differs between countries: check the label and your public health authority's guidance. Boiling, filters and tablets — and how much treated water each gives you for a long outage — are covered in the full guide.
Water
Storing, filtering and disinfecting water when the power and the tap are both gone
Worksheets (appendices)
- The Water Is Off — What First?
- Personal Water Plan
- Labels for Water Containers
- Water Supply Log
- Equipment by Priority
- Local Information Card
- Worked Example — Apartment and House
Sources: CDC — Making Water Safe in an Emergency; WHO — Technical notes on drinking-water, sanitation and hygiene in emergencies. Sources are listed on the last page of every guide.
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