How is chlorine residual measured?

Chlorine residual is measured in milligrams per liter (mg/L) because this unit effectively expresses the concentration of chlorine present in water. This measurement indicates the amount of chlorine available for disinfection purposes, which is crucial for ensuring water quality and safety in distribution systems.

When assessing the effectiveness of chlorination processes, it is important to know the concentration levels, as insufficient residual levels can lead to inadequate disinfection of pathogens, while excessive levels can result in taste and odor issues and may pose health risks.

The other units such as parts per billion (ppb) do indicate concentration but are more commonly used for trace contaminants rather than for more substantial disinfection measures. Similarly, liters per hour (L/h) is a measure of flow rate, which is unrelated to concentration, and percentage is typically used to express proportions in different contexts, making milligrams per liter the most appropriate measurement for chlorine residual in water distribution.