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Chlorine Taste and/or Odor

In Pennsylvania, all public drinking water systems are required to have a disinfection residual in the drinking water at all times to protect against potential contamination prior to use.  This residual is referred to as a “secondary residual”, as it follows an initial application of disinfection, or “primary disinfection” which is applied at the source.  The most common forms of secondary disinfection residuals used are either chlorine by itself or chlorine in combination with ammonia (referred to as chloramines).  Chlorine by itself is a much stronger disinfectant than chloramines, but it is not as persistent (i.e., chlorine residuals decay faster than chloramine residuals).   Larger systems will typically use chloramines due to its stability, but smaller systems, such as Horsham, prefer to use chlorine by itself due to the stronger disinfection strength.

In 2018, Pennsylvania Department of Environmental Protection (PADEP) passed the Disinfection Requirements Rule (DRR) which raised the minimum secondary residual to 0.2 mg/l, which is higher than federal requirements, for all water systems in the state.  Since chlorine residuals will decay while in the water distribution system pipes and storage tanks, water systems must apply a higher dosage at the sources to ensure the minimum residual remains higher than 0.2 mg/l at all times in the system.  Typically, all of the Horsham Water & Sewer Authority’s sources will have an initial level of 2.0-2.5 mg/l depending on time of the year (residuals will decay faster in warmer water months).  People have varying degrees of sensitivity to chlorine taste and odor in water and these levels can be perceived as displeasing to some.  Unfortunately, the need to sustain a healthy residual throughout the entire system to protect human health mandates we maintain these levels.

If the chlorine taste and odor is unpleasant to you, the good news is that chlorine is very easy to remove through either simple home treatment devices/filters or simply through ‘aging” the water.  Some people have found maintaining a pitcher of tap water in the refrigerator to use for drinking can reduce the levels such that the chlorine taste and/or odor is not perceptible. Although the residual will dissipate more quickly at room temperatures than in a refrigerator, the taste can be less noticeable in waters having a colder water temperature.