At lower water temperatures, how does the kill rate for chlorination change?

At lower water temperatures, the effectiveness of chlorination in disinfecting water typically decreases. This is because the reaction rate between chlorine and pathogens is slower at lower temperatures, leading to a lower overall kill rate. Consequently, to achieve the same level of disinfection, higher chlorine residuals must be maintained in the water.

Maintaining increased residuals ensures that there is enough chlorine present to compensate for the reduced efficacy at lower temperatures, thereby ensuring that pathogens are adequately killed and the water remains safe for consumption. This phenomenon is important in water distribution systems, as temperature variations can significantly impact water quality and safety measures.