The practice of purifying water with household bleach is a widely accepted technique for making water safe to drink when normal sources are compromised. This method focuses on disinfection, using the active ingredient, sodium hypochlorite, to kill harmful microorganisms like bacteria and viruses. While this process effectively neutralizes biological pathogens, it will not remove chemical pollutants, heavy metals, or other non-living contaminants. If the water is suspected to contain such contaminants, disinfection with bleach alone is not sufficient to make it potable.
Essential Prerequisites: Selecting the Right Bleach
The effectiveness of this purification method depends entirely on using the correct type of bleach. Select a plain, regular, liquid household bleach that is unscented and free of additives like color-safe agents, gels, or perfumes. These additives can be harmful if ingested and interfere with the disinfection process. The label should clearly state that the active ingredient is sodium hypochlorite, typically within a concentration range of 5% to 9%.
Before adding any disinfectant, the water must be relatively clear. Excessively cloudy or turbid water contains suspended particles that can shield microorganisms from the chlorine, significantly reducing its effectiveness. If the water is not clear, it must first be filtered through a clean cloth, paper towel, or coffee filter to remove debris. Alternatively, allow the water to settle for several hours, then carefully draw off the clear water from the top for treatment.
Precise Dosage Calculation for 5 Gallons
The precise measurement of bleach is based on achieving a target concentration of chlorine in the water, measured in parts per million (ppm). For clear water using a standard household bleach concentration of 5.25% to 6.0% sodium hypochlorite, the recommended dosage for 5 gallons is 1/2 teaspoon. This delivers a disinfecting level of free chlorine safe for consumption. Use a clean measuring spoon to ensure accuracy and prevent cross-contamination.
If your bleach concentration is higher, such as 8.25%, slightly reduce the amount used to prevent an overly strong chlorine concentration. Since 8.25% is a more potent solution, using approximately 3/8 teaspoon for 5 gallons is a safe adjustment. This maintains the effective level of hypochlorous acid, the compound that kills pathogens, without exceeding safe residual limits. Always confirm the percentage on your product label, as concentrations can vary between brands and regions.
Step-by-Step Water Disinfection Procedure
Once the precise dosage has been measured, the purification process involves several straightforward steps. Carefully add the measured amount of bleach directly into the 5-gallon container of water. Securely seal the container with its lid. Mixing is accomplished by shaking the container vigorously for several minutes or stirring thoroughly with a clean utensil to ensure the chlorine is uniformly distributed.
The chlorine requires a specific amount of time, known as contact time, to effectively kill harmful pathogens. The treated water must stand for a minimum of 30 minutes before it is considered safe to drink. After this contact time, sniff the water for a faint, residual chlorine odor. A slight smell indicates that enough chlorine remains after reacting with the microorganisms, confirming successful disinfection.
If you cannot detect any chlorine smell after the initial 30 minutes, the bleach was entirely consumed by organic matter and pathogens, meaning disinfection was incomplete. In this scenario, repeat the initial dosage of bleach and allow the water to stand for an additional 15 minutes. If you still do not detect a faint chlorine odor after this second waiting period, the water source is too contaminated for this method and should be discarded or treated differently.
Safety Checks and Common Mistakes
A common outcome of purification is the water having a strong chlorine taste or odor, which is unpleasant but harmless. If the smell is too intense, aerate the water to reduce the concentration of chlorine gas. Pour the water back and forth between two clean containers several times; the increased surface area exposure allows the excess chlorine to dissipate into the air.
Label the container clearly with the date and contents immediately after treatment and store it in a cool, dark location away from direct sunlight. When handling bleach, never mix it with other cleaning products, especially those containing ammonia or acids. Combining bleach with these substances can release highly toxic chlorine or chloramine gases, creating an immediate health hazard.