What is required to protect the potable water supply in systems with chemical additives or antifreeze?

To protect the potable water supply in systems that utilize chemical additives or antifreeze, a reduced pressure principle backflow preventer is the most suitable device. This type of backflow preventer is specifically designed to prevent backflow due to either backpressure or back siphonage conditions. The reduced pressure principle requires that the pressure in the area of the device be kept lower than that of the potable water supply, creating a barrier that prevents contaminated water from entering the clean water piping system.

In systems where chemical additives or antifreeze are present, there is a significant risk of pollutants entering the potable water supply should a cross-connection occur. A reduced pressure principle backflow preventer tackles this concern effectively, maintaining a safe and secure boundary between the potentially contaminated system and the drinking water supply.

The other options, while providing some level of protection, do not offer the same level of security against the specific risks posed by chemicals or antifreeze, making them less suitable for this particular application.