For a potable water connection to a boiler feed water system, what installation is necessary where chemicals are introduced?

For a potable water connection to a boiler feed water system where chemicals are introduced, the installation of an air gap or a reduced pressure principle backflow preventer is essential to protect the drinking water supply. This is because the introduction of chemicals into the boiler feed water creates a risk of backflow if there is a drop in pressure within the system.

The air gap provides a physical separation between the potable water supply and the non-potable water used in the boiler system, ensuring that harmful substances cannot siphon back into the drinking water. A reduced pressure principle backflow preventer serves a similar function by allowing water to flow only in one direction, effectively preventing back-siphonage caused by pressure changes.

Both methods are critical in maintaining the safety and integrity of the potable water supply, particularly when chemicals are present that could contaminate it. This level of protection is necessary in any system that could potentially introduce pollutants into the clean water supply, thus adhering to health regulations and ensuring public safety.