Diluted bleach is a great value for a sanitizer. For a food-safe dilution, you want a 200 ppm solution. Dilution tables are handy, but how does one calculate the precise amount of bleach to use, especially when your bleach is an atypical concentration?

The label on my bleach jug says it "yields 7.86% available chlorine." I want to prepare a 1 liter spray bottle. Then the calculation is

This is about one-half teaspoons (0.5 tsp.) of my 7.86% bleach in 1 liter of water. This result is right in line with the "2 teaspoons of bleach per gallon of water" rule of thumb!

### Other Considerations

• Bleach is inactivated by organic material. You need to use a detergent to clean any surface before sanitizing it with diluted bleach.
• Bleach is also inactivated by heat and light. Use an opaque container, and store it in a cool, dark place.

\frac{ 200 \;\; \text{ppm} \;\; \times \;\; 1 \;\; \text{L} }{ 7.86\% } = 0.002545 \;\; \text{L} = 2.545 \;\; \text{mL}