Tap water often contains chlorine, a common additive used in public water systems. While chlorine serves an important purpose in ensuring water safety, many people are interested in understanding how this chemical leaves water and what methods can help facilitate its removal at home. This article explores the natural processes of chlorine dissipation and practical techniques to reduce its presence in tap water.
The Purpose of Chlorine in Water Supply
Chlorine is added to tap water primarily as a disinfectant. Its role is to kill harmful bacteria, viruses, and other microorganisms that could cause waterborne diseases. This disinfection process is a standard practice by municipal water treatment plants, maintaining public health and safety by preventing the spread of pathogens through drinking water. Water utilities have employed chlorine for over a century to ensure water remains safe as it travels through extensive pipe networks to homes.
Natural Dissipation of Chlorine
Free chlorine in tap water is a volatile substance, meaning it readily converts from a liquid to a gas and escapes into the air over time. This natural dissipation occurs when water is exposed to the atmosphere. For instance, a glass of tap water left uncovered can become mostly chlorine-free within 24 hours. A larger volume, like a 5-gallon bucket, may take several days, typically 4 to 5 days, for complete chlorine evaporation.
Several factors influence the rate at which free chlorine dissipates. Increasing the water’s surface area, such as by using a wide bowl instead of a narrow bottle, allows for faster evaporation. Warmer water temperatures accelerate this process, as the increased kinetic energy of water molecules encourages dissolved chlorine gas to escape more quickly. Movement or agitation of the water, like stirring or pouring, also increases air exposure and speeds up dissipation. Sunlight can also contribute to the breakdown and evaporation of chlorine.
Speeding Up Chlorine Removal
Various methods can accelerate chlorine removal from tap water. Boiling water speeds up the evaporation of chlorine. A rolling boil for 15 to 20 minutes can reduce free chlorine levels. This method utilizes chlorine’s low boiling point, causing it to volatilize rapidly as the water heats.
Aeration or agitation techniques also enhance chlorine dissipation by increasing contact between water and air. Simply pouring water back and forth between two containers, stirring vigorously, or using a spray nozzle can help. For water left to sit out, using wide-mouthed containers maximizes surface area.
Filtration offers another effective approach. Activated carbon filters, commonly found in pitcher filters or faucet attachments, remove chlorine by converting it into harmless chloride ions. This method is fast. Chemical neutralization provides a rapid solution, especially for larger volumes. Ascorbic acid, commonly known as Vitamin C, quickly neutralizes chlorine through a redox reaction.
Chloramine Considerations
Many water systems use chloramine, a compound formed by combining chlorine and ammonia, as a disinfectant. Chloramine is more stable than free chlorine, meaning it does not dissipate easily by letting water sit out or by boiling. Water utilities often opt for chloramine because it provides longer-lasting disinfection in distribution pipes and produces fewer disinfection byproducts.
Removing chloramine requires different strategies. While some activated carbon filters can reduce chloramine, more specialized filtration, such as catalytic carbon, might be necessary for effective removal. These filters remove chloramine through a chemical reaction that breaks it down into safer compounds. Chemical treatments designed specifically for chloramine are also available.
It is advisable to contact local water utilities to determine if their water contains chlorine or chloramine, as this information influences the most effective removal strategy. For specific applications, such as filling fish tanks or watering sensitive plants, ensuring chloramine removal is important.