What is chlorine residual in water?

Chlorine residual refers to the concentration of chlorine that remains in water after the chlorine demand has been met. This is crucial in water treatment processes as it indicates the amount of chlorine available to provide ongoing disinfection. When chlorine is added to water, it first reacts with various contaminants, such as organic matter and microorganisms. The chlorine residual is the leftover amount after these reactions, which ensures that the water remains disinfected as it travels through the distribution system.

Understanding this concept is vital for maintaining water quality and safety because it allows water treatment professionals to verify that there is sufficient disinfection throughout the system. Without an adequate chlorine residual, the treated water could become recontaminated before reaching consumers, potentially posing health risks. Therefore, measuring and maintaining the chlorine residual is a key responsibility for water treatment operators.