Which type of chlorine residual is most likely to cause taste and odor problems?

Dichloramine is known to contribute to unpleasant taste and odor issues in treated water. It forms when free chlorine reacts with ammonia or organic nitrogen compounds in water, leading to the creation of chloramines. While free chlorine and hypochlorous acid can also have effects on water quality, they typically do not cause the same level of taste and odor problems associated with dichloramine.

Combined chlorine, which includes both monochloramine and dichloramine, can lead to similar issues if present in high concentrations, but dichloramine specifically is often singled out due to its stronger association with off-putting tastes and aromas. Thus, in the context of this question, dichloramine stands out as the type of chlorine residual most likely to result in noticeable taste and odor problems in chlorinated water systems.