Which method does NOT prevent backsiphonage?

Backsiphonage occurs when the pressure in a plumbing system drops, causing contaminated water to be drawn back into the clean water supply. To combat this, various methods are utilized to create barriers that prevent this reverse flow.

Air gap separation is an effective method for preventing backsiphonage because it creates a physical air gap between the water supply and any potential contaminants, ensuring that no siphoned water can return to the system. Vacuum breakers are devices that allow air to enter the system when a negative pressure occurs, thus stopping backsiphonage before it happens. Hydrostatic loops work by maintaining a proper pressure level that prevents the backflow of liquids, making them effective in this context as well.

Backpressure units are designed to handle situations where pressure in the downstream system exceeds that of the supply, but they do not inherently prevent backsiphonage caused by negative pressure scenarios. This is why the method that does not effectively prevent backsiphonage is hydrostatic loops, as their primary function is not related to addressing negative pressure situations but rather to ensure proper flow rates and pressure management under specific conditions.