In plumbing terms, what does 'backflow' refer to?

Backflow in plumbing specifically refers to a situation where water moves in the opposite direction from its intended path, typically reversing the flow of water within a plumbing system. This can occur due to changes in pressure, such as when there is a drop in the water supply pressure or a surge in drainage.

Understanding backflow is crucial because it can lead to contamination of the potable water supply when unsanitary waters, like those from sinks or toilets, re-enter clean water lines. This term is particularly significant when considering public health and safety, as backflow can introduce harmful substances and bacteria into drinking water systems.

The other options pertain to different plumbing issues but do not accurately describe backflow. Improper drainage refers to water not flowing correctly within drainage systems, water leakages are about water escaping from pipes, and blocked pipes indicate obstructions preventing water flow. Each of these issues can negatively impact a plumbing system, but none relate directly to the reversal of water flow, which is the core of backflow.