Water Treatment Operator-in-Training (OIT) 2025 – 400 Free Practice Questions to Pass the Exam

When a sewer is surcharged, it means that the flow of water in the sewer system exceeds its capacity, leading to an overflow situation. This scenario typically occurs during heavy rainfall, flooding, or when there is a blockage within the sewer line, causing water to back up and exert additional pressure on the system. Hydraulically overloading a sewer can result in sewage spills, which pose significant environmental and public health risks.

In contrast, the other options do not accurately describe what happens during a surcharge. For instance, stating that a sewer becomes too dry contradicts the concept of surcharging, which involves excess water. Similarly, suggesting that a sewer is under maintenance does not account for the overflow condition, which is more of an emergency situation than routine maintenance. Finally, the implication of more water being pumped in is misleading; a surcharge refers to an existing volume of water that exceeds the sewer's design flow rather than additional pumping of water into the system.