What is the optimal pH range to minimize eye irritation while maintaining effective residual chlorine?

The optimal pH range of 7.5 to 7.6 is considered effective for minimizing eye irritation while ensuring that chlorine retains its disinfecting properties. Chlorine is commonly used in water treatment due to its ability to kill pathogens, but its effectiveness is affected by pH.

When the pH is maintained within this range, the balance between the free chlorine (hypochlorous acid) and combined chlorine (hypochlorite) is optimized. Hypochlorous acid is more effective as a disinfectant and less irritating to the eyes. If the pH exceeds 7.8, the concentration of free chlorine diminishes, making it less effective, and if it falls below 7.2, the likelihood of eye irritation increases significantly.

Thus, maintaining the pH within the target range of 7.5 to 7.6 ensures the water remains safe and comfortable for users while sustaining effective residual chlorine levels for disinfection.