Which term describes the reverse water flow caused by a vacuum in a water supply main?

The term that describes reverse water flow caused by a vacuum in a water supply main is backsiphonage. This phenomenon occurs when there is a drop in pressure within the water supply system, leading to the backflow of water from an outlet into the main supply line. This typically happens during events such as a sudden demand for water, a break in the water main, or when a fire hydrant is opened for use, which can create a negative pressure zone that allows water to flow backwards.

Understanding backsiphonage is essential for mitigating risks associated with contamination in potable water supplies. For instance, if water from a source that contains pollutants is pulled back into the clean water supply due to backsiphonage, it can lead to serious public health issues. Therefore, it's crucial to implement appropriate backflow prevention methods to safeguard drinking water systems.

Other terms, while related to water flow or plumbing issues, do not specifically describe this reverse flow phenomenon. For example, a cross connection refers to an actual physical connection between a drinking water supply and a source of contamination. Water hammering pertains to the noise and shock waves that occur in pipes due to sudden changes in water flow, and an air gap line is a physical separation used to prevent backflow,