What is the minimum free chlorine residual required in water systems?

• A. 1.0 Mg/L
• B. 0.5 Mg/L
• C. 0.2 Mg/L
• D. 2.0 Mg/L

Answer: (C)

The minimum free chlorine residual required in water systems is typically set to ensure adequate disinfection and to protect public health. A residual of 0.2 mg/L allows for effective control of pathogens while maintaining a low enough concentration to prevent any adverse effects on water quality or taste. This minimum level ensures that there is sufficient chlorine remaining in the water after treatment, which helps to minimize the risk of microbial contamination as the water travels through the distribution system.

Maintaining this level is crucial for effective water treatment, as it helps in the prevention of waterborne diseases. To ensure compliance with health and safety standards, water treatment facilities monitor chlorine levels constantly, aiming to maintain a balance that is effective for disinfection but not excessive. This practice is supported by regulatory guidelines aimed at safeguarding public health while providing safe drinking water.