What is one main function of a check valve in a backflow prevention system?

A check valve's primary function in a backflow prevention system is to allow water to flow in only one direction. This is critical for maintaining the integrity of the water supply and preventing contaminated water from flowing back into clean water lines. By facilitating unidirectional flow, the check valve effectively blocks any potential reverse flow that could introduce pollutants or harmful substances into the potable water system. This characteristic is essential for safety standards in plumbing systems and contributes to public health protection.

Other functions listed, such as boosting water pressure or filtering impurities, do not align with the core role of a check valve. Check valves are specifically designed for flow direction control and do not serve as pressure regulators or filters in a backflow prevention system. Similarly, measuring water flow is not a function of a check valve, as this would require different types of devices designed for monitoring flow rates. Overall, the unidirectional flow capability of a check valve is indispensable for effective backflow prevention.