Final answer:
A backflow preventer is a device that is used to prevent wastewater from flowing back into clean water lines, and it is often used in combination with a check valve to maintain water supply integrity.
Step-by-step explanation:
The concept described in the question refers to a backflow preventer which is designed to ensure that any wastewater or unwanted materials do not flow back into clean water lines. The devices like a check valve may allow fluids to move in one direction while preventing reverse flow. This is important in both residential and industrial settings to protect the potable water supply from contamination.
Situations where backflow prevention is crucial include when dealing with indirect waste receptors or appliances that are indirectly connected to the sewer system. One example is when a physical separation between the lower inlet of the wastewater and the receptor is necessary to prevent backflow. Another example is water treatment plants using a bar screen to remove large debris from water to prevent damage to the equipment.
Backflow preventers and check valves serve as critical components in maintaining the integrity of water supply systems by avoiding pollutants from entering water supplies including from point sources like wastewater treatment plants or during situations like heavy rains causing sewer overflows.