What is back siphonage?

Back siphonage refers to a specific type of backflow that occurs when there is a negative pressure in the water supply system, causing water to flow backward. This phenomenon can happen when there is a sudden drop in pressure in the supply line, often due to events such as a water main break or excessive withdrawal of water from the system. The resulting pressure difference leads to the non-potable water being drawn into the potable water supply, potentially causing contamination.

Understanding this concept is crucial in the design and implementation of irrigation systems, as preventing back siphonage is vital for maintaining water quality and ensuring safe water for irrigation and consumption.

The other options describe different scenarios related to water flow and pressure but do not accurately encapsulate the mechanics of back siphonage as it specifically involves the conditions that lead to a reverse flow caused by a pressure difference in the system.