What it means
A cross-connection is a link between potable water and a potential contaminant. Backflow can occur when pressure reverses direction. Prevention methods include air gaps, reduced-pressure assemblies, double-check assemblies, and vacuum breakers depending on hazard level.
What operators watch
- Air gaps provide strong protection when properly maintained.
- Backpressure and backsiphonage are different causes of reverse flow.
- Device selection depends on hazard type and local rules.
Common exam traps
- Confusing cross-connection with backflow.
- Treating all backflow devices as interchangeable.
- Forgetting that testing and recordkeeping are part of many programs.
Field example
A chemical feed connection without proper isolation can become a cross-connection hazard if system pressure drops or chemical-side pressure rises.
