What does the total chlorine residual include?

The total chlorine residual is a measure that encompasses both free chlorine and combined chlorine. Free chlorine refers to the amount of chlorine available in water to disinfect and kill pathogens, while combined chlorine consists of chloramines, which are formed when chlorine reacts with ammonia or organic nitrogen compounds in the water.

Measuring total chlorine residual is essential for understanding the effectiveness of chlorination in water treatment processes. It helps determine how much chlorine has been consumed in reactions versus how much is available for disinfection. Monitoring both free and combined chlorine is vital in ensuring water safety and compliance with regulatory standards.

The other options focus on individual components of chlorine rather than the total measurement, which is why they do not accurately reflect what the total chlorine residual includes.