Ontario Operator-in-Training (OIT) Practice Exam

Backflow siphonage is typically caused by?

1. High pressure in the water main

2. Negative pressure in the water main

3. Excessive demand on the water supply

4. Low chlorine residual

The correct answer is: Negative pressure in the water main

Backflow siphonage typically occurs when there is negative pressure in the water main. This negative pressure can create a condition where water is drawn back into the potable water supply from non-potable sources, leading to potential contamination. This situation is often a result of sudden changes in the water system, such as a pipe break or excessive demand that creates a vacuum in the system. Understanding backflow prevention is crucial for maintaining water quality. The creation of negative pressure can disrupt the normal flow of water, causing a siphoning effect where contaminants can enter the clean water supply. Effective management of water pressure, ensuring robust infrastructure, and implementing backflow prevention devices are essential strategies to mitigate these risks.