What is a pressure vacuum breaker (PVB) used for?

A pressure vacuum breaker (PVB) is specifically designed to prevent backsiphonage in non-potable water systems. Backsiphonage occurs when there is a drop in water pressure, which can lead to contaminated water being drawn back into the clean water supply. The PVB utilizes a spring-loaded valve that opens to relieve pressure when it drops too low, preventing the reverse flow of potentially harmful contaminants into the potable water supply. This function is critical in maintaining the integrity of the drinking water system, particularly in applications where non-potable water might be used, such as irrigation or industrial processes.

The other choices do not accurately describe the primary function of a PVB; while maintaining consistent water pressure and filtering debris are important aspects of water management, they are not the purpose of a PVB. Additionally, preventing water from freezing is not within the operational capabilities of a PVB.