Contaminant: Chlorine [free (Cl0)]
FREE CHLORINE COMMENTARY

Water treatment devices approved for the reduction of free chlorine (Cl0) will reduce the taste and odor some consumers find objectionable caused by the chlorination of water.  Free chlorine is added to water in the form of a gas (Cl2), a liquid [sodium hypochlorite (NaHClO)] or a solid [calcium hypochlorite (CaHClO)].  Free chlorine does not include the consideration of combined forms of chlorine (i.e. chloramines), which can also have a pronounced effect on the taste and odor of water.  The devices do not actually remove the free chlorine, but convert free chlorine to chloride (Cl-); chloride does not have an odor and does not affect taste until its concentration reaches much higher levels.

Water treatment devices approved for free chlorine reduction are also approved for the reduction of certain organic taste and odor causing compounds of biologic origin, specifically geosmin and 2-methylisoborneol which are responsible for imparting unpleasant earthy/musty tastes and odors in water supplies.  This is possible because, via testing, free chlorine reduction has been shown to be a suitable surrogate for the reduction of geosmin and 2-methylisoborneol.

Other contaminants that may adversely impact the taste and odor of water, such as hydrogen sulfide, are not covered under an approval for free chlorine, taste and odor reduction.