What issue is commonly noticed when overfeeding chlorine (CL2)?

When chlorine is overfed into a water treatment system, it can lead to the formation of disinfection byproducts, primarily chlorinated compounds known as dichloramine (Di CL2) and trichloramine (Tri CL2). These compounds are often associated with noticeable taste and odor issues in treated water. Overfeeding chlorine can disturb the balance of the system, leading to nitrification, which is the conversion of ammonia into nitrates and can further exacerbate the presence of these chlorinated compounds in the water.

The presence of Di and Tri chloramines is infamous for causing undesirable tastes and smells that can deter consumers from using the water. This effect occurs because excess chlorine reacts not only with organic materials but also with ammonia present in the water, producing these chlorinated species, which are typically considered off-putting.

This option focuses on the direct correlation between chlorine overfeed and the resultant taste and odor problems, making it the correct choice. Understanding this relationship is vital for those working in water treatment, as it highlights the importance of balancing chlorine dosing to maintain water quality and avoid consumer complaints.