What is the result of pre-chlorination intended to remove tastes and odors?

Pre-chlorination is a water treatment process primarily aimed at removing tastes and odors from the water supply. One of the significant outcomes of introducing chlorine during the pre-chlorination stage is the potential formation of trihalomethanes (THMs). THMs are organic compounds that are formed when chlorine reacts with natural organic matter found in water, such as humic and fulvic acids. The presence of these compounds in the water is important to monitor because they can have health implications if consumed in large amounts.

While the process may lead to a variety of changes in the water's chemistry, the formation of THMs is particularly notable because it highlights a paradox of chlorination: while chlorination is effective for disinfection and taste/odor control, it can also create unwanted byproducts that may pose risks to public health. This understanding is crucial for water operators, as they must balance effective treatment with the minimization of harmful byproducts in the water supply.

Other options, while they may have some relation to water quality, do not directly pertain to the primary goal of pre-chlorination in removing tastes and odors as THM formation does.