What is the primary function of an anti-siphon device in an irrigation system?

The primary function of an anti-siphon device in an irrigation system is to prevent backflow, ensuring that contaminated water does not siphon back into the potable water supply. By allowing air to enter the system, it effectively breaks the vacuum that could lead to backflow. This mechanism is crucial for maintaining the safety of the drinking water supply by ensuring that any potentially polluted water remains contained within the irrigation system and does not mix with clean water sources.

While the other options may relate to various functions in an irrigation system, they do not align with the specific purpose of an anti-siphon device. The energy supply of the pump circuit, measurement of water pressure, and regulation of flow rates are all essential aspects of a well-managed irrigation system, but they do not address the critical preventive measure that the anti-siphon device serves in safeguarding water quality.