When public water sources are compromised, emergency water disinfection is necessary. Household bleach, which contains sodium hypochlorite, is a highly effective method for neutralizing harmful microorganisms. This process, known as chlorination, kills bacteria, viruses, and other pathogens that cause illness. This approach converts questionable water into a safer source for drinking and cooking.
Selecting the Correct Type of Bleach
The safety of using bleach for water disinfection depends on selecting the correct product. Only regular, unscented liquid household bleach is appropriate. The label must indicate the bleach is for disinfection and contain only sodium hypochlorite as the active ingredient.
The concentration of sodium hypochlorite typically ranges from 5% to 9% in standard household products. Avoid formulations that include scents, colors, or additives like thickeners or cleaners. These extra components introduce chemicals unsafe for human consumption. If the bottle does not list the sodium hypochlorite percentage or is outside the 5% to 9% range, it should not be used for treating drinking water.
Precise Dosage for One Gallon of Water
The precise dosage for one gallon of water depends on the sodium hypochlorite concentration. For a common concentration of 5% to 6%, the standard measurement is 8 drops of liquid bleach per gallon. This is approximately 1/8 of a teaspoon and should be measured using a clean dropper or sterile spoon.
More concentrated bleach products (8.25% sodium hypochlorite) require 6 drops per gallon. Before treatment, the water should be visibly clear; filter it through a clean cloth or allow sediment to settle if necessary. If the water remains cloudy or is significantly colder than room temperature, double the dosage to 16 drops per gallon to ensure sufficient antimicrobial action.
Completing the Purification Process
After adding the drops, mix the solution thoroughly to ensure the disinfectant is distributed evenly. Stir the container or seal and shake it for a minute to blend the bleach completely. The water must then be allowed a minimum contact time of 30 minutes for the sodium hypochlorite to neutralize pathogens effectively.
Success is determined by checking for a faint chlorine smell in the treated water. A slight scent indicates enough chlorine was added to kill microorganisms and that a residual amount remains to protect against recontamination. If no chlorine odor is detectable after 30 minutes, repeat the original dosage and let the water stand for another 15 minutes before re-checking. If the water tastes too strongly chlorinated, improve it by aeration: pour the water back and forth between two clean containers several times.