What is a vacuum breaker and what is its purpose?

A vacuum breaker is specifically designed to prevent backflow in plumbing systems. Its primary purpose is to stop the reverse flow of water, which can occur when there is a drop in pressure within the system, such as during system drainage or when a faucet is opened. This is crucial in maintaining safe water quality and preventing contamination as it ensures that water does not flow back into the potable supply from potentially contaminated sources.

In contrast, the other options address different functions that are not related to the role of a vacuum breaker. Increasing water pressure is outside of its scope, as is testing water quality or regulating water temperature—all of which serve different aspects of plumbing system management. Understanding the specific function of a vacuum breaker highlights its importance in safeguarding the integrity of water supplies.