What happens to chlorine demand when organic material is left inside a replaced water main?

When organic material remains inside a replaced water main, it significantly affects the chlorine demand within the system. Chlorine is commonly used as a disinfectant to eliminate pathogens in water, but it can also react with organic matter present in the water distribution system, leading to increased chlorine demand.

As chlorine interacts with the organic material, a considerable amount of chlorine is consumed in these reactions, which results in a decrease in the amount of chlorine that remains available as a residual after these reactions occur. Consequently, the cumulative effect is an increase in chlorine demand and a decrease in chlorine residual. This is critical for water treatment and distribution because adequate chlorine residual is essential to ensure that the water remains safe from microbial contamination as it travels through the distribution system.

Understanding this relationship between organic material, chlorine demand, and chlorine residual helps water system operators manage and maintain effective disinfection practices, ensuring the safety and quality of drinking water for consumers.