What is the maximum allowable chlorine residual in drinking water systems?

The maximum allowable chlorine residual in drinking water systems is set at 4.0 mg/L. This level is established based on the need to ensure effective disinfection while minimizing potential health risks. Chlorine is widely used as a disinfectant in drinking water to eliminate harmful pathogens and bacteria. However, excessively high levels can lead to adverse health effects as well as unpleasant tastes and odors, which could discourage people from drinking water.

The regulatory agencies, such as the Environmental Protection Agency (EPA), dictate this standard to help maintain a balance between adequate disinfection and consumer safety. Monitoring and managing chlorine levels is crucial for water operators to ensure the safety and quality of drinking water for the public. Adhering to this maximum level helps protect both public health and maintains the integrity of the water supply system.