What condition usually occurs due to backsiphonage?

Backsiphonage typically occurs when there is a negative pressure in the water distribution system, which can lead to a condition where contaminated water is pulled into the potable water supply. This negative pressure can happen due to incidents like a main break or heavy water withdrawal from the system. When the pressure drops, it creates a vacuum that can draw standing water or contaminated water from lower-lying sources back into the drinking water supply.

This phenomenon directly correlates with reduced pressure in the system. Maintaining proper pressure levels is critical to ensure that water flows in the intended direction and to prevent backflow of contaminants. While backsiphonage can lead to various repercussions like contamination, the primary condition that facilitates this issue is indeed reduced pressure in the water distribution system.