What is a disadvantage of using free chlorine?

The use of free chlorine in water treatment comes with several advantages, but also notable disadvantages, one of which is the formation of trihalomethanes (THMs). When chlorine reacts with organic matter present in the water, it can lead to the production of these chemical compounds. THMs are chlorinated organic compounds that, while effective for disinfection, can pose health risks when they are present in elevated concentrations. This concern arises from various studies indicating a potential link between THMs and certain health issues, making their formation a significant drawback to utilizing free chlorine as a disinfectant.

At the same time, free chlorine does provide residual disinfection, which helps to maintain water quality throughout the distribution system and it is relatively stable under many conditions, which makes it easier to manage. Moreover, it is generally one of the more cost-effective disinfectant options compared to other methods. Understanding these dynamics is crucial for water treatment professionals who need to balance method efficacy with potential health hazards.