What is the recommended free chlorine residual for the furthest point in the water distribution system?

The recommended free chlorine residual for the furthest point in the water distribution system is generally set at a level that ensures adequate disinfection while mitigating the risk of harmful pathogens. A free chlorine residual of 0.2 mg/L is acknowledged as a minimum to provide sufficient sanitation while remaining safe for consumers. This concentration is aimed at ensuring that water reaching the most distant service connections maintains chlorine levels that can effectively inhibit bacterial growth, thus protecting public health.

Using too low a residual, such as 0.1 mg/L, may not adequately ensure disinfection throughout the distribution system, especially at endpoints that can experience decreased levels of chlorine due to factors like water age and pipe materials. Similarly, although higher levels like 0.5 mg/L or 0.8 mg/L can provide a stronger disinfection benchmark, they may be unnecessary in many systems and could lead to taste or odor complaints from consumers. Therefore, 0.2 mg/L is positioned as a balanced target for safe and effective water treatment in distribution systems.