What is the required chlorine residual for pools?

The required chlorine residual for pools is crucial for maintaining safe and hygienic water conditions. The correct answer, indicating a range of 1 to 5 ppm (parts per million), is based on standard public health guidelines that help ensure effective disinfection while minimizing the potential for irritation or other adverse effects for swimmers.

A chlorine residual of 1 to 5 ppm is generally recognized as adequate for preventing the growth of harmful pathogens and maintaining water clarity. Within this range, it's also important for pool operators to monitor factors such as pH levels, temperature, and bather load, as these can affect the efficacy of chlorine in the water.

The upper and lower limits of this range provide flexibility for operators to adjust chlorine levels based on specific circumstances, ensuring that water remains safe and pleasant for pool users. Maintaining levels within this range also helps to reduce the risk of unpleasant odors or skin irritation that can occur if chlorine levels become too high. Therefore, the 1 to 5 ppm specification is both practical and effective for achieving the balance needed for safe swimming environments.