What is the acceptable level of free chlorine in swimming pool water?

The acceptable level of free chlorine in swimming pool water is typically maintained at 1 to 3 parts per million (ppm) for effective sanitation. This range is crucial for ensuring that the chlorine can effectively kill bacteria, viruses, and other pathogens, providing a safe swimming environment. However, certain conditions, such as high bather loads or very high temperatures, might require adjustments.

In the context of this question, the range of 2 to 20 parts per million is broader than what is recommended for normal operational conditions. While levels above the recommended range can be safe for brief periods, consistently maintaining free chlorine at such high levels (especially approaching 20 ppm) can lead to issues including skin and eye irritation for swimmers as well as a potential decrease in water balance and clarity.

Ideal management practices focus on keeping free chlorine between 1 to 3 ppm for standard swimming conditions, aligning with health regulations and recommendations. While regular testing and monitoring of chlorine levels are essential, maintaining a level much higher than this in routine situations can be counterproductive and harmful to both the swimmers and the pool infrastructure.