Combined residual chlorine should be maintained in the range of?

The correct range for maintaining combined residual chlorine, which is a measure of chlorine that remains in the water after it has reacted with ammonia and other compounds, is critical for effective disinfection while minimizing potential harmful effects. Maintaining a combined residual chlorine level within the range of 1.0 to 2.0 mg/L is optimal as it ensures sufficient disinfecting power to eliminate pathogens and prevent bacterial regrowth in the distribution system.

This range is also consistent with regulatory standards aimed at ensuring safe drinking water, as it helps to maintain a balance between effective microbial control and minimizing the potential for forming harmful disinfection byproducts. A level above 2.0 could lead to taste and odor issues while levels lower than 1.0 may not provide adequate protection against harmful microorganisms.

Levels below 1.0 mg/L may not effectively control bacterial growth, leading to compromised water quality. Similarly, while options like 0.5-1.0 and 0.3-0.7 offer some degree of disinfection potential, they fall short for comprehensive pathogen control. The option of 0.1-0.5 is significantly below the recommended level and would not ensure proper disinfection efficacy. Therefore, maintaining the higher range of 1.0