Back-siphoning prevention can be ensured by which combination?

• A. Air gaps
• B. Anti-siphoning devices
• C. Both air gaps and anti-siphoning devices
• D. None of the above

Answer: (C)

Back-siphoning is prevented by creating a barrier that stops water from flowing backward into the supply when pressure changes. An air gap does this by placing a physical separation between the water outlet and the receiving vessel, so contaminated water can’t be drawn back into the source. An anti-siphoning device (such as a vacuum breaker) prevents siphoning by allowing air into the line and breaking any developing suction, even if pressure drops.

Using both provides the strongest protection because they cover different scenarios: the air gap is a simple, reliable physical separation, while the anti-siphon device guards against siphon effects in systems where a gap isn’t feasible or where pressure conditions could still create backflow. If one component isn’t present or isn’t functioning, the other can still offer protection, and together they maximize safety. Regular maintenance and proper installation are essential to keep both barriers effective.