Prechlorination is performed at which point in the treatment process?

Prepare for the American Water Works Water Treatment Plant Operator Test. Study with multiple choice questions, each with hints and explanations. Get ready to excel!

Prechlorination means injecting chlorine early in the treatment train so disinfection begins before other treatment steps. Doing this at the headworks—the point where raw water first enters the plant and undergoes screening and initial treatment—puts chlorine in the water right away, helping to inactivate microorganisms, suppress biological growth, and provide a disinfectant residual as water moves through coagulation, sedimentation, and filtration. If chlorine were added after filtration, at the outlet, or only in the clearwell, it would be post-treatment disinfection or residual maintenance for distribution, not early protection of the treatment processes. So, the headworks is the appropriate location for prechlorination.