Backflow Prevention Practice Exam

Which of the following can be a source of contamination if an air gap is not properly maintained?

1. Sewage systems

2. Stormwater runoff

3. Industrial discharge

4. Potable water supplies

The correct answer is: Sewage systems

An air gap is a critical factor in backflow prevention, serving as a physical barrier that prevents contaminated water from flowing back into a clean water supply. If this air gap is not properly maintained, it fails to provide the necessary protection against contaminants. Among the options, sewage systems represent a significant source of contamination. When an air gap is compromised, contaminated water from sewage systems can backflow into potable water supplies, leading to serious public health risks. Sewage contains pathogens and harmful substances that can contaminate drinking water, making the maintenance of an effective air gap essential to safeguard against these hazards. Stormwater runoff and industrial discharge can also contribute to contamination issues, but they typically pose risks in different contexts related to water quality and environmental protection, rather than directly through a compromised air gap. Potable water supplies are the endpoint that needs to be protected, and while they can be at risk from other factors, the direct threat due to a failure in maintaining an air gap primarily concerns sewage systems. Thus, understanding how an air gap works and the specific sources of contamination involved highlights why sewage systems are particularly notable in this context.