What is the definition of backsiphonage?

Backsiphonage refers to a specific type of backflow that occurs when there is a drop in supply pressure, causing the water flow to reverse. This situation commonly arises when the pressure in a water system decreases below atmospheric pressure, creating a vacuum. As a result, water from the lower-pressure side can be drawn back into the potable water supply, potentially bringing contaminants along with it.

Understanding backsiphonage is critical for maintaining safe drinking water supplies, as it can lead to the introduction of harmful substances into clean water systems. The other options don't accurately describe backsiphonage; for instance, an increase in supply pressure typically results in normal flow direction rather than a reversal, and contaminant pressure doesn't directly correlate to the definition of backsiphonage. A method to reduce pressure is also unrelated to the concept of backflow dynamics.