When is chlorine available to kill bacteria in pool water?

Chlorine is available to kill bacteria in pool water immediately when added to the water, which is fundamental to its function as a disinfectant. When chlorine is introduced into the water, it starts to interact with bacteria and other microorganisms right away, effectively oxidizing and killing them.

While breakpoint chlorination is a crucial concept in water treatment, achieving this state specifically refers to a level of chlorination required to eliminate combined chlorine, thereby ensuring that free chlorine levels are available for disinfection. This process is important for maintaining clear and safe water but does not negate the fact that chlorine begins its disinfection action as soon as it is added.

The idea that chlorine is effective only at high levels, such as above 10 ppm, is not accurate either. Chlorine can begin to act at much lower concentrations; the effectiveness of chlorine does not solely depend on reaching excessive levels. The primary goal is to maintain an appropriate free chlorine level that is effective for disinfection, typically between 1 to 3 ppm for most pools.

In summary, the effectiveness of chlorine as an immediate bactericide upon addition to water is the key factor, thus reinforcing that chlorine's disinfecting properties activate as soon as it is present in the water.