Household liquid bleach can be an effective chemical disinfectant for water, especially in emergency situations when boiling is not possible. This method leverages chlorination, a process used globally for over a century to make community water supplies safe. The technique treats water suspected of containing harmful microorganisms, such as bacteria and viruses, which cause waterborne illnesses. While boiling is the most reliable method, chemical treatment with bleach offers a viable alternative when fuel or time is limited. The active ingredient creates a residual disinfectant that continues to protect the water after initial treatment.
Essential Bleach Requirements for Safe Disinfection
The success and safety of using bleach for water treatment depend entirely on selecting the correct product. Only regular, unscented liquid household bleach is suitable. The label must confirm that the active ingredient is sodium hypochlorite, typically present in a concentration ranging from 5% to 9%. Concentrations outside this range require careful dosage adjustment.
Avoid all bleach products that contain additives, fragrances, color-safe agents, or are marketed as “splash-less” or “gel” formulas. These extra components are not intended for ingestion and can introduce toxic substances into the drinking water. The bleach must rely solely on the chemical properties of sodium hypochlorite for disinfection.
Step-by-Step Water Purification Process
The process begins with a crucial preparatory step: clarifying the water, especially if it appears cloudy or turbid. Turbidity, caused by suspended particles like dirt or sediment, can shield microorganisms from the disinfectant, reducing its effectiveness. Cloudy water should first be filtered through a clean cloth, paper towel, or coffee filter to remove particulate matter.
Once the water is visibly clear, the appropriate amount of bleach can be added. For clear water, a commonly cited ratio is 8 drops of regular household bleach (6% sodium hypochlorite) per one gallon of water. If the concentration is higher, such as 8.25%, the dosage is reduced to 6 drops per gallon. If the water remains cloudy after filtering, or if it is very cold, the recommended dosage should be doubled.
After adding the correct amount of bleach, the water must be thoroughly mixed and allowed to stand for a minimum of 30 minutes. This waiting period is the necessary contact time that allows the chlorine to kill pathogens. Following the contact time, the water should have a slight chlorine odor, confirming successful disinfection and residual disinfectant remains. If no chlorine smell is detectable, the dosage should be repeated, and the water allowed to stand for an additional 15 minutes before consumption.
Limitations of Chlorine Treatment
While chlorination is a powerful tool against many waterborne pathogens, it is not a comprehensive purification solution. Chlorine is highly effective at neutralizing most common bacteria and viruses, but its efficacy is limited against certain hardy organisms. Protozoan cysts, such as Cryptosporidium and Giardia, possess tough outer shells that make them resistant to the chlorine levels used in emergency disinfection.
Chemical disinfection with bleach does not remove non-biological contaminants from the water. Heavy metals, chemical pollutants, oils, and fine particulate matter will remain after treatment. Therefore, the water source should be as clean as possible, and pre-filtering to remove sediment is necessary. If the water source is suspected of containing toxic chemicals or is dark-colored or odorous, it should not be consumed, as chlorine cannot mitigate these dangers.
A common side effect of chlorination is a strong taste or odor caused by the chlorine residual or its reaction with organic matter. To improve palatability, the water can be aerated by pouring it back and forth several times between two clean containers. Alternatively, allowing the water to stand uncovered for a few hours permits the excess chlorine gas to dissipate, reducing the noticeable taste and smell.