What constitutes a closed system in plumbing?

A closed system in plumbing typically refers to a configuration that prevents the mixing of drinking water with non-potable water sources or contaminants. Backflow prevention assemblies play a crucial role in this context because they are specifically designed to stop the reverse flow of water, which could carry pollutants back into a potable water supply. By creating a barrier, these devices help ensure that the drinking water system remains isolated and protected from contamination, effectively maintaining the integrity of the closed system.

In contrast, atmospheric regulators and open pipe systems do not provide the same level of protection from backflow or contamination. Atmospheric regulators are designed to control pressure and may not prevent backflow, while open pipe systems are inherently susceptible to environmental contaminants since they do not have safeguards. Non-potable connections can also lead to cross-contamination if not properly managed, thus failing the definition of a closed system. Therefore, backflow prevention assemblies are essential in establishing the framework of a closed plumbing system, ensuring safe and reliable water supply practices.