What is the purpose of breakpoint chlorination?

Breakpoint chlorination refers to the process of adding chlorine to water until the combined chlorine (chloramines) is converted entirely back into free chlorine. This is essential for maintaining water quality in pools, as combined chlorine can cause irritation to the skin and eyes, produce unpleasant odors, and generally impact the safety and enjoyment of the swimming environment.

When performing breakpoint chlorination, the goal is to reach a point where the ratio of free chlorine to combined chlorine allows the free chlorine to effectively neutralize the chloramines. This process typically requires a significant amount of chlorine—often 10 times the amount of the combined chlorine present—thus ensuring all the unwanted compounds are oxidized.

Maintaining a constant chlorine level, eliminating chlorine completely, or lowering pH levels address different water chemistry concerns but do not specifically target the direct issue of combined chlorine management. By focusing on neutralizing combined chlorine, breakpoint chlorination improves overall water quality and swimmer safety, which is why this choice is considered the correct answer.