Ace the California Wastewater Treatment Operator Exam 2026 – Dive In and Purify Your Career!

The correct answer is influent, which refers to the wastewater that flows into a treatment plant for processing. This is the initial stage of wastewater treatment, where the raw sewage or wastewater from various sources, such as homes, industries, and stormwater runoff, arrives at the facility.

Understanding this terminology is crucial for anyone working in wastewater treatment, as it sets the stage for the entire treatment process. The influent undergoes various treatment stages designed to remove contaminants and pollutants before the cleaned water is released or reused.

Other options like effluent and supernatant do not relate to what enters the headworks. Effluent refers to treated water that is discharged from the treatment plant, while supernatant describes the clear liquid that remains above settled solids after sedimentation processes, typically occurring in secondary treatment stages. Thus, these terms represent outputs or byproducts within the treatment process, not what initially enters the facility.