When water is delivered to homes, it is treated at a municipal facility with a disinfectant to eliminate pathogens like bacteria and viruses. This process, often involving chlorine, is a public health measure that ensures the water remains safe throughout the distribution system. Many people notice a distinct, sometimes unpleasant, taste or odor in their tap water and wonder if a simple kitchen method like boiling can effectively remove this residual chemical. The answer depends heavily on the specific disinfectant used by the water utility.
The Science of Chlorine Removal Through Boiling
Boiling reduces the concentration of free chlorine in water through a process called volatilization. Chlorine is a highly volatile substance, meaning it readily transitions from a dissolved state to a gaseous state. As the water temperature rises, the solubility of a gas in a liquid decreases, forcing the dissolved chlorine molecules out of the solution. The rolling boil accelerates this process significantly. This method is an effective way to reduce the concentration of free chlorine, which is often responsible for the chemical taste and odor in tap water.
Practical Steps for Effective Chlorine Evaporation
To achieve a significant reduction in free chlorine, the water must be boiled for a specific duration in an open container. While chlorine begins to off-gas as soon as the water heats up, a rapid, rolling boil is needed for substantial removal. A general recommendation is to boil the water for approximately 15 to 20 minutes. The use of an uncovered pot with a wide opening is important because it maximizes the water’s surface area exposed to the air, allowing the released chlorine gas to escape efficiently. Once the boiling time is complete, the water must be allowed to cool completely before consumption, as the process only removes the chlorine.
Addressing the Chloramine Difference
The effectiveness of boiling changes considerably when a water utility uses chloramine instead of free chlorine. Chloramine is a compound formed by combining chlorine and ammonia, designed to provide a stable, longer-lasting disinfectant residual throughout the distribution system. This stability makes chloramine far less susceptible to removal by boiling. Chloramine is less volatile than free chlorine, meaning it does not easily convert to a gas and escape the water when heated. While boiling for 15 to 20 minutes is effective for free chlorine, it provides minimal reduction for chloramines; extended boiling is highly impractical and can actually concentrate non-volatile contaminants like heavy metals or nitrates as the water evaporates.
Alternative Methods for Removing Chlorine and Chloramines
Since boiling is often inefficient, especially for chloramine, other techniques are widely used for chemical removal. The most common alternative is activated carbon filtration. Activated carbon filters, found in pitchers, faucet mounts, and whole-house systems, work through adsorption, where the chlorine or chloramine molecules become trapped on the filter’s highly porous surface. For water containing chloramines, a specialized material known as catalytic carbon is often required, as it is designed to break down the stable chloramine bond. Simple methods can also offer some reduction; leaving water to stand in an open container for 24 to 48 hours allows free chlorine to naturally off-gas, or adding ascorbic acid (Vitamin C) powder can instantly neutralize both chlorine and chloramine.