AWWA Water Treatment Operator Certification Practice Test

Chloramines are typically formed during the post-chlorination stage of water treatment. This process involves the addition of ammonia to water that has already been chlorinated. The combination of chlorine with ammonia produces chloramines, which serve as a more stable and long-lasting disinfectant in the distribution system. This is particularly important for maintaining water quality as it prevents the regrowth of pathogens in the pipelines.

In contrast, pre-chlorination refers to the initial application of chlorine before other treatment processes, primarily for controlling algae and bacteria in raw water. Filtration is a process used to remove particles and contaminants from water, but it does not involve the formation of chloramines. Coagulation is the step where chemicals are added to help remove suspended particles through agglomeration, and again does not involve chloramines. Therefore, the accurate formation stage of chloramines is post-chlorination.