Chlorine has been used to disinfect public water supplies in the United States since the early 1900s, and its introduction is credited with dramatically reducing waterborne diseases like typhoid fever and cholera. The basic function is simple: chlorine kills bacteria, viruses, and other pathogens that could cause illness if consumed. Without disinfection, distribution systems that carry water through miles of pipe before it reaches your tap would be far more dangerous.

Chloramine — a compound formed by combining chlorine with ammonia — became more widely adopted as a secondary disinfectant starting in the 1990s, largely in response to regulations around disinfection byproducts. Chloramine is more stable than free chlorine, meaning it maintains its disinfectant properties longer through a distribution system without forming as many of the regulated byproducts that chlorine produces. Many Metro East municipalities use chloramine as their primary or secondary disinfectant.

The most common complaint about chlorinated water is taste and odor. Chlorine has a distinct smell that many people find unpleasant, particularly at higher concentrations or when water has been sitting in a glass. Chloramine produces a different but equally recognizable chemical smell. Neither is considered a health hazard at regulated levels, but both affect the palatability of tap water and can influence cooking and beverage preparation.

Activated carbon filtration — either in a pitcher filter, under-sink unit, or whole-home system — is highly effective at removing chlorine taste and odor. Chloramine is more resistant than free chlorine and requires catalytic carbon or extended contact time with standard carbon to achieve effective reduction.

At the levels used in municipal water treatment, chlorine and chloramine are not considered direct health hazards for the general population. The EPA's Maximum Residual Disinfectant Level (MRDL) for chlorine is 4 mg/L; for chloramine it's also 4 mg/L. Most municipal systems operate well below these limits.

There are specific populations for whom chloramine is a more significant concern. Dialysis patients cannot use chloramine-treated water in dialysis machines without additional treatment, as chloramine passes through dialysis membranes and can cause hemolytic anemia. Fish and amphibians are also highly sensitive — chloramine cannot be neutralized with standard dechlorination tablets and requires specific treatment before chloramine-treated water is used in aquariums or ponds.

The longer-term health concern associated with chlorine and chloramine isn't the compounds themselves but the byproducts they form when they react with organic matter in the water — a separate topic covered in our disinfection byproducts guide.

For taste and odor alone, a quality activated carbon filter — pitcher, faucet-mounted, or under-sink — handles chlorine effectively and is among the most cost-effective improvements a homeowner can make. For chloramine, look for filters specifically rated for chloramine reduction, which typically means catalytic carbon.

Whole-home treatment makes sense when the goal is to remove chlorine or chloramine from all water in the house, including bath and shower water. Inhalation of chlorine vapors during hot showers is a real but often overlooked exposure pathway, particularly in tightly sealed homes. A whole-home carbon system addresses this comprehensively.