Public water systems commonly add chlorine to their water supply, a process known as chlorination. This serves as a primary method of disinfection, ensuring water safety. The main purpose of adding chlorine is to kill harmful microorganisms, including bacteria, viruses, and protozoans, which can cause waterborne illnesses. This widely adopted practice helps prevent diseases like cholera, typhoid fever, and dysentery, protecting public health.
The Role of Chlorine in Water Treatment
Chlorine functions as a potent disinfectant in water treatment by destroying harmful microorganisms like bacteria, viruses, and protozoans. It achieves this through oxidation, forming compounds that disrupt cellular structures of pathogens.
A significant advantage of chlorine is its residual property, meaning it remains active in the water as it flows through distribution networks. This continuous presence helps maintain water quality and prevents recontamination from the treatment facility to the tap. Chlorination’s widespread adoption is also attributed to its cost-effectiveness, making it a cornerstone of public health protection.
Considerations for Chlorine Removal
Chlorine in tap water can be undesirable in various situations. Many perceive a distinct taste and odor, often described as bleach-like, which affects the palatability of drinking water and prepared foods.
Chlorine is also highly detrimental to aquatic organisms, even at low concentrations typical of municipal water. Levels between 0.1 and 0.3 parts per million can be lethal to fish, damaging gill tissues and disrupting their internal systems. Eliminating chlorine from water for aquariums is thus necessary to protect aquatic life.
Chlorine can also negatively influence specific chemical processes. In brewing, for instance, it may react to produce undesirable flavors. Similarly, certain sensitive plants, such as orchids, can experience damage to their root systems when irrigated with chlorinated water.
Household Approaches to Chlorine Removal
Several simple methods can remove chlorine from water at home. One common approach is allowing water to stand, or “aging.” Chlorine is a volatile compound that dissipates into the air over time. Leaving tap water in an open container for approximately 24 hours, especially at room temperature, allows most free chlorine to evaporate.
Boiling water accelerates this evaporation process. Chlorine has a much lower boiling point than water, so as water heats, chlorine molecules quickly volatilize and escape. Boiling water in an uncovered pot for 15 to 20 minutes can significantly reduce free chlorine levels. However, neither standing nor boiling effectively removes chloramine, a more stable disinfectant composed of chlorine and ammonia.
Aeration, introducing air into water, also aids in chlorine removal by increasing gas exchange. This can be achieved by vigorously stirring water, pouring it between containers, or using an air stone. The increased surface area contact with air facilitates the quicker escape of chlorine gas. These household methods are primarily limited to free chlorine, not chloramine.
Specialized Filtration and Chemical Treatments
For more comprehensive chlorine removal, specialized filtration and chemical treatments offer advanced solutions. Activated carbon filters function through adsorption and catalytic reduction. These filters, including granular and carbon block types, effectively remove chlorine and chloramine, enhancing water taste and odor in various systems, from pitcher filters to whole-house units.
Chemical neutralization provides a direct method for immediate chlorine removal. Sodium thiosulfate rapidly neutralizes chlorine and chloramine by converting them into non-toxic substances. Ascorbic acid (Vitamin C) and sodium ascorbate also effectively neutralize both chlorine and chloramine. These are utilized in contexts such as aquariums, agriculture, and medical procedures like dialysis.
Reverse osmosis (RO) systems offer comprehensive water purification. While the RO membrane itself does not remove chlorine, these systems integrate activated carbon pre-filters. This pre-filtration step is essential to eliminate chlorine, which would otherwise damage the delicate RO membrane. The overall RO process effectively reduces a broad spectrum of contaminants, providing high-quality treated water.