What is a probable cause of a drop in chlorine level in water treatment?

A drop in chlorine level in water treatment can occur due to an increase in chlorine demand. When chlorine is added to water, its effectiveness can be diminished by various factors such as organic materials, biological activity, and the overall quality of the influent water. If there is a higher concentration of contaminants, such as organic matter or ammonia, the chlorine will react with these substances, leading to a higher demand for chlorine. As a result, the residual chlorine—the amount of chlorine remaining after the reaction—will decrease because more chlorine is being consumed to maintain water quality. This highlights the importance of monitoring chlorine levels as a key indicator of water treatment efficiency and effectiveness.