What is formed when all chlorine demand is met?

When all chlorine demand is met, a chlorine residual is formed. Chlorine demand refers to the amount of chlorine that is required to react with various substances in the water, such as organic matter, bacteria, and other compounds that can consume chlorine.

Once all of these demand reactions have taken place and the chlorine has successfully interacted with those impurities, any remaining chlorine that does not get used up is known as the chlorine residual. This residual is important because it indicates the amount of chlorine that is still present in the water to continue disinfecting and protecting against the regrowth of microorganisms as the water is distributed through the system.

Maintaining an adequate level of chlorine residual is critical for effective water treatment. It serves as a measure of the efficacy of the chlorination process and ensures that the water remains safe for consumption. Chlorine gas, chlorine demand, and chlorinated organics represent different concepts in the context of water treatment and do not apply to the requirement of having an unspent amount of chlorine that stays in the system.