In emergency situations, household bleach offers a chemical solution for disinfecting water. This process uses the active ingredient, sodium hypochlorite, to kill harmful microorganisms that cause illness. When boiling is not possible, chemical purification provides a reliable method to make water potable. This guide outlines the specific procedure for purifying one gallon of water using bleach.
Selecting the Correct Bleach Formula
The first step for safe purification is selecting the correct type of bleach, as not all products are suitable for consumption. Only plain, unscented, regular household bleach should be used for treating drinking water. Check the label to confirm the product contains only sodium hypochlorite and water, with no added cleaners, scents, or thickeners.
The concentration of sodium hypochlorite is important, with most household concentrations ranging from 6% to 9%. This range is effective for water disinfection when used in the correct dosage. Products labeled as “splash-less,” color-safe, or those with scents must be avoided because their additives are unsafe for human consumption and can introduce toxic compounds into the water.
Measuring and Applying Bleach
The dosage is calculated to achieve a residual chlorine level that kills pathogens. For one gallon of clear water, the standard measurement is 8 drops of regular bleach (6% to 8.25% sodium hypochlorite concentration). Use a clean medicine dropper to ensure precise measurement, as free-pouring can lead to a slight overdose. Once the drops are added, the water must be thoroughly mixed to distribute the disinfectant.
If the water is cloudy, colored, or very cold, the dosage should be doubled to 16 drops per gallon. Cloudy water contains suspended particles that can shield microorganisms from the sodium hypochlorite, requiring a higher concentration for proper contact. After the appropriate dosage is applied and mixed, the treated water must stand for a minimum of 30 minutes.
Confirming Effectiveness and Safe Storage
After the 30-minute contact time, the water’s safety is confirmed by the presence of a slight chlorine odor. This faint smell indicates that enough chlorine neutralized the pathogens and that a small residual amount remains to prevent recontamination. If there is no detectable chlorine odor after the initial waiting period, repeat the dose and allow the water to stand for an additional 15 minutes.
If a slight chlorine odor is still not present after the second treatment, the water should be discarded, and a different source should be found. This suggests the bleach may have been too weak or the water too contaminated. Once the water has been successfully treated and the slight chlorine scent is present, it is safe to consume.
The purified water should be stored in clean, covered containers to maintain its safety. Household bleach has a limited shelf life and its potency degrades over time, often losing about 20% of its strength per year. For this reason, it is advisable to replace the bleach used for emergency purification annually to ensure maximum effectiveness.