The presence of a chlorine-like smell in tap water is a common concern. This odor is typically a direct result of the necessary disinfection process that keeps public water supplies free of harmful microbes. Even when the smell is noticeable, the water remains perfectly safe to drink and use. The distinct odor indicates that the disinfectant, which protects the water on its journey to your home, is present and active.
The Role of Chlorination in Water Safety
Chlorine is added to public drinking water systems as a highly effective disinfectant. Its primary function is to eliminate disease-causing pathogens, such as bacteria and viruses, that can lead to waterborne illnesses. The widespread use of chlorination is regarded as one of the most significant advancements in public health history.
The process maintains a measurable amount of chlorine, known as a residual, throughout the entire distribution network. This residual acts as a safeguard, preventing the growth of microorganisms and protecting the water from potential contamination while it travels to your tap. Without this persistent protection, the safety of the water supply could be compromised before it reaches the consumer.
Safety Standards for Residual Chlorine
Federal regulations establish strict limits for the amount of disinfectant allowed in public water supplies to ensure safety. The U.S. Environmental Protection Agency (EPA) sets a Maximum Residual Disinfectant Level (MRDL) for chlorine at \(4.0\text{ milligrams per liter (mg/L)}\). This limit is the maximum concentration that may not be exceeded due to the possibility of adverse health effects.
The concentration of chlorine that causes a noticeable odor is often far below this regulatory limit. Many individuals can detect the bleach-like smell at concentrations as low as \(0.05\text{ to }0.6\text{ mg/L}\). Therefore, the water is safe for consumption even if the smell is strong enough to be unpleasant. Treatment facilities maintain a level effective for disinfection while remaining within the safety parameters set by the EPA.
When a Strong Odor Requires Attention
Temporary Increases
While a faint chlorine odor is normal, a sudden, intense, or overwhelming smell may indicate a temporary change in the water system. Water utilities sometimes intentionally increase chlorine levels to address maintenance activities, such as flushing water mains or cleaning storage tanks. Seasonal changes, particularly in warmer weather, can also prompt facilities to temporarily boost chlorine to better control microbial growth.
Location and Chloramines
A strong, persistent odor can be more noticeable in homes closer to the water treatment plant, as the chlorine has not had as much time to dissipate. Another factor is the formation of chloramines, disinfectants created when chlorine reacts with ammonia. Chloramines are more stable than free chlorine and provide longer-lasting protection, but they can contribute to a more noticeable chemical odor.
When to Contact the Utility
Consumers should contact their water utility if the chlorine odor is overwhelming and does not dissipate after running the cold water for a few minutes. This is especially important if the strong smell is accompanied by other changes, such as a noticeable shift in water color or taste. If the odor is only present at one faucet, the issue is likely related to the household’s internal plumbing, such as the water heater or a drain that needs cleaning.
Reducing Chlorine Taste and Smell in Tap Water
Simple Methods
For consumers who find the taste or smell of chlorine unpalatable, several practical methods can be used for reduction. Since chlorine is volatile, meaning it easily turns into a gas, simply letting the water sit out allows the chemical to dissipate. Filling a pitcher and refrigerating it for a few hours can significantly reduce the odor and improve the taste.
Advanced Reduction Techniques
Boiling tap water for 10 to 15 minutes can accelerate the volatilization of free chlorine, though this is less effective for stable chloramines. The most effective method for both chlorine and chloramine removal is filtration using activated carbon. Activated carbon filters, found in pitchers, faucet mounts, and whole-house systems, work through adsorption, trapping chlorine molecules within the carbon media. For an immediate, chemical-free solution, a small amount of ascorbic acid, or Vitamin C, can be added to a glass of water to instantly neutralize the chlorine compounds.