What does pH measure in pool water?

The correct answer highlights that pH measures the level of acidity or alkalinity in the water. In pool water, maintaining the appropriate pH level is crucial because it affects both water quality and the effectiveness of sanitizers like chlorine. A pH level below 7 indicates acidity, which can lead to corrosion of pool equipment and surfaces, and may irritate the skin and eyes of swimmers. Conversely, a pH level above 7 indicates alkalinity, which can cause scale formation and reduce the effectiveness of chlorine in killing pathogens.

Understanding pH is essential for maintaining a safe and comfortable swimming environment. The ideal pH range for pool water is typically between 7.2 and 7.8, where chlorine works best and swimmer comfort is maximized. Thus, monitoring and adjusting pH levels is a fundamental aspect of pool management and public health safety.