Chlorine is a common disinfectant added to public water supplies. Its role is to eliminate harmful microorganisms like bacteria and viruses, ensuring water is safe for consumption and preventing waterborne diseases. This practice has been standard for over a century.
Why Chlorine is in Water and How it Leaves
Water treatment facilities add chlorine to drinking water to kill disease-causing germs and maintain safety as it travels through pipes to your tap. Once in your home, chlorine leaves water primarily through two mechanisms: evaporation and degradation. Evaporation involves chlorine gas dissipating into the air, as chlorine is a volatile compound. Degradation occurs when chlorine reacts with other substances, such as organic matter, or is broken down by ultraviolet (UV) light. Both processes reduce chlorine levels in standing water.
Factors Affecting Chlorine Dissipation
Several factors influence how quickly chlorine dissipates from water. Higher temperatures accelerate evaporation, as warmer water causes chlorine to volatilize more rapidly than colder water. The surface area exposed to air also impacts the rate of dissipation; a larger surface area allows more chlorine molecules to escape into the atmosphere.
Agitation or aeration, which involves stirring or moving the water, increases contact between water and air, speeding up chlorine release. Initial chlorine concentration affects the time to reach zero; higher levels take longer to become chlorine-free. Sunlight, particularly its UV component, can break down chlorine. The presence of organic matter can also react with and consume chlorine, contributing to its degradation.
Speeding Up Chlorine Removal
Several practical methods can quickly remove chlorine. Simply letting water sit in an open container allows natural evaporation, though this can be time-consuming, potentially taking 24 hours or more. Boiling water for 15-20 minutes significantly speeds up evaporation due to increased temperature and agitation. However, this method is better suited for smaller volumes of water.
Aeration techniques, such as stirring water vigorously or pouring it between containers, enhance chlorine gas release. Chemical neutralizers, like sodium thiosulfate or vitamin C (ascorbic acid), can instantly neutralize chlorine by converting it into harmless compounds. These are often available as drops or tablets. Activated carbon filters effectively remove chlorine through adsorption, trapping molecules within their porous structure. These filters are found in various forms, including pitcher filters, faucet attachments, and whole-house systems.
When Chlorine-Free Water Matters
Removing chlorine from water is important for specific applications where its presence can be detrimental. For watering plants, chlorine can harm beneficial microorganisms in the soil essential for nutrient cycling and overall plant health. It can also interfere with nutrient uptake and potentially damage root cells, leading to stunted growth or yellowing leaves.
For fish tanks, chlorine is toxic to aquatic life, even at low concentrations, causing gill damage, respiratory problems, and stress. It also eliminates beneficial bacteria necessary for the aquarium’s nitrogen cycle, which can lead to dangerous ammonia spikes. Some individuals prefer chlorine-free water for drinking due to taste or odor. To confirm chlorine has dissipated, test strips or liquid test kits are available, which change color to indicate its presence and concentration.