Which of the following is a method for determining levels of chlorine in water?

The chlorine residual test is specifically designed to measure the amount of chlorine present in water, indicating how much chlorine is available for disinfection purposes. This method quantifies both free chlorine, which is active and effective in killing pathogens, and total chlorine, which includes both free and combined chlorine species. Understanding the residual chlorine levels is crucial for ensuring that water treatment processes are effectively managing microbial contamination and maintaining safe drinking water standards.

The pH test determines the acidity or alkalinity of water, which can influence chlorine effectiveness but does not measure chlorine levels directly. The dissolved oxygen test measures the oxygen content in water, relevant for assessing ecological health but unrelated to chlorine concentration. The turbidity test assesses the clarity of water based on particle suspension, which can affect disinfection processes but does not provide specific information about chlorine levels. Thus, the chlorine residual test is the most appropriate and relevant method for determining levels of chlorine in water.