What mechanism is used to protect against backsiphonage and backflow?

The mechanism used to protect against backsiphonage and backflow is a reduced pressure zone assembly. This device is specifically designed to prevent contaminated water from entering the potable water supply. It operates by maintaining a reduced pressure in the system, which ensures that any backflow that may occur does not pass through to the drinking water lines.

In a reduced pressure zone assembly, there are two valves and a pressure differential sensor. When water flows normally, it allows flow through the system. However, if there is a drop in pressure that could lead to backsiphonage, the assembly functions to maintain the pressure difference necessary to prevent backflow. This is crucial in protecting public health by ensuring that potential contaminants do not enter the drinking water supply.

While check valves and air gaps are also mechanisms for preventing backflow, reduced pressure zone assemblies are preferred in situations where there is a significant risk of contamination, as they provide a more reliable means of maintaining safe drinking water standards. Filtration, on the other hand, serves a different purpose focused on removing particulates and sediments but does not specifically address the issue of backflow or backsiphonage.