What does the term "backflow" refer to in plumbing?

The term "backflow" in plumbing is correctly defined as the reverse flow of non-potable water into a potable water supply. This phenomenon can occur when there is a change in pressure within the plumbing system, which allows contaminants from non-potable sources, such as irrigation systems or industrial processes, to flow back into drinking water supplies. This is a critical concern because it poses health risks, potentially contaminating the water that is safe for consumption and use.

To prevent backflow, plumbing systems are equipped with various devices such as backflow preventers, which are designed to stop this reverse flow and ensure that drinking water remains uncontaminated. Understanding backflow and its implications is essential for maintaining the safety and integrity of water supplies in residential plumbing systems.