Which method is used to determine the efficiency of chlorination?

The method used to determine the efficiency of chlorination is through residual testing. This process involves measuring the amount of chlorine that remains in the water after the chlorination process, which is referred to as the "chlorine residual." This is crucial because a sufficient residual indicates that the chlorine has effectively disinfected the water and that some amount remains to protect against possible contamination as the water moves through the distribution system.

Residual testing not only helps confirm that adequate chlorination has taken place but also assists in assessing the effectiveness of the chlorine in killing pathogens in the water. The results from residual testing can guide operators in adjusting chlorine doses and ensuring that water quality standards are met throughout the entire water distribution system.

Other methods mentioned, while important in their own right, do not directly measure the effectiveness of the chlorination process itself. Flow measurement focuses on the volume of water processed and is not specific to chlorination efficiency. Physical inspections might assess equipment or facilities but lack quantitative assessment of chlorine levels. Chlorine concentration adjustment involves changing the chlorine levels but does not evaluate the existing effectiveness of the chlorination that has already occurred.