In what scenario would a backsiphonage occur?

Backsiphonage occurs when there is a negative pressure or a vacuum created in a water system, causing water to flow back into the system from a source that should not be connected to it. This situation can arise from various conditions, such as a sudden drop in pressure due to a water main break or when there is excessive demand for water, leading to a drop in system pressure.

When vacuum conditions develop, they create an environment where the pressure in the supply line is lower than in the contaminating source. This allows contaminants to be drawn back into the potable water supply through cross-connections, posing a significant risk of contamination.

While other scenarios listed may have impacts on water flow or pressure, they do not create the necessary vacuum conditions required for backsiphonage to occur. Understanding this concept is crucial for ensuring safe and clean drinking water by preventing contamination through established plumbing protocols.