What is the purpose of a backflow preventer?

The purpose of a backflow preventer is to protect the potable water supply from contamination. Backflow occurs when water flows in the opposite direction to its intended flow, which can happen due to changes in pressure within the system. This can potentially allow contaminants from non-potable sources, such as wastewater or chemicals, to enter the clean water supply. The backflow preventer acts as a safeguard by ensuring that water can only flow in one direction, thus preventing any backflow that might carry harmful substances into the drinking water supply.

This is critical for public health and safety, as ensuring that clean water remains uncontaminated is a top priority in plumbing and water management. The other options, while related to various aspects of plumbing systems, do not address the primary function of a backflow preventer, which is solely focused on contamination prevention.