REFERENCE // TOOL

Water Purification Dosing

Disinfect a volume of water with unscented household bleach, at the current EPA / CDC emergency doses.

Disinfect a volume of water with unscented household bleach. Figures are the current EPA / CDC emergency-disinfection doses.

Volume

Unit

Bleach strength (on the label)

Water clarity

Bleach to add

Then let stand

30 min

Per-unit dose

How it works

Clear water: 2 drops per liter at 5–6% (8 per gallon), or 6 per gallon at 8.25%. Cloudy water doubles the dose — and must be pre-filtered through cloth and settled first. After 30 minutes the water should smell faintly of chlorine; if not, repeat the dose and wait another 15 minutes. Bleach does not remove chemicals or radioactive material, and works less well than boiling against Cryptosporidium and Giardia.

Source: EPA — Emergency Disinfection of Drinking Water · CDC — Making Water Safe in an Emergency (verified 2026).

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