How is the term 'influent' defined in water systems operations?

The term 'influent' in the context of water systems operations is defined as water or liquid flowing into a treatment plant. This encompasses any incoming water that is processed at the facility, including raw wastewater from municipal sources or industrial discharges that require treatment before it is safe to release back into the environment or reuse. Understanding this distinction is essential for anyone involved in environmental management or water treatment processes, as it highlights the starting point in the treatment cycle.

In contrast, the other options focus on different aspects of the water management process. Outflow from treatment plants, such as effluent, refers to the treated water that leaves the facility. Wastewater discharged from industrial sources pertains to specific types of influent but does not cover the broader definition. Rainwater collected during storms is often classified as stormwater and may be treated differently than standard influent, indicating that it is a separate category of water management. Thus, option B accurately represents the definition of influent.