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

The recommended level of free chlorine in swimming pool water is typically between 1 to 5 parts per million (ppm). This range is considered optimal for maintaining safe and sanitary water conditions for swimmers. Free chlorine is the active form of chlorine that effectively kills harmful bacteria and pathogens in the pool, thereby contributing to public health and safety.

Maintaining the free chlorine at this level ensures that there is sufficient disinfection without causing irritation or discomfort to swimmers. Levels that are too low may not effectively sanitize the water, potentially leading to health risks, while levels that are too high can cause skin and eye irritation, as well as unpleasant odors.

Higher ranges such as 15 to 20 ppm and 2 to 20 ppm could be excessive for regular swimming conditions, as they may lead to irritation and are generally not advisable for continuous use. The option suggesting 2 to 15 ppm is also outside the standard recommended range, particularly at the upper end, which could create similar issues associated with overly chlorinated water. Thus, the safest and most effective level to maintain in swimming pools is indeed 1 to 5 parts per million of free chlorine.