Off Grid Living WisdomHow Much Bleach to Purify Water
How much bleach to purify water depends on the bleach strength and how much water you have. Enter the gallons and your bleach's strength, and this free calculator gives the drops and teaspoons, following EPA guidance. Below it, a second calculator shows how much emergency water to store.
EPA bleach doses for drinking water
| Clear water | 6% bleach | 8.25% bleach |
|---|---|---|
| 1 quart | 2 drops | 2 drops |
| 1 gallon | 8 drops | 6 drops |
| 2 gallons | 16 drops | 12 drops (1/8 tsp) |
| 4 gallons | 1/3 tsp | 1/4 tsp |
| 8 gallons | 2/3 tsp | 1/2 tsp |
How to purify water with bleach
- Use regular unscented chlorine bleach. Never scented, color-safe or "with added cleaners."
- If the water is cloudy, let it settle and pour it through a clean cloth or coffee filter first.
- Add the dose from the calculator and stir.
- Wait 30 minutes. The water should smell slightly of chlorine. If it doesn't, repeat the dose and wait 15 more minutes.
Boiling works too: a full rolling boil for 1 minute, or 3 minutes above 6,500 feet. Bleach weakens with age, so replace your emergency bottle every year.
How much emergency water to store
FEMA recommends 1 gallon per person per day, for at least 3 days and ideally 2 weeks. Add more for hot weather, illness, nursing mothers and pets.
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Frequently asked questions
How much bleach do I need to purify a gallon of water?
8 drops of regular 6% unscented bleach per gallon of clear water, or 6 drops of 8.25% bleach (EPA). Double it for cloudy, colored or very cold water.
How long do I wait after adding bleach?
30 minutes. The water should have a faint chlorine smell. If it doesn't, add the same dose again and wait another 15 minutes.
Can I use scented or splashless bleach?
No. Use only regular unscented chlorine bleach. Scented, color-safe and “added cleaner” products contain chemicals you shouldn't drink.
How much water should I store for an emergency?
1 gallon per person per day, for at least 3 days and ideally 2 weeks. A family of four needs 56 gallons for two weeks, before pets and hot weather.