What does a check valve do in plumbing?

A check valve is designed to facilitate the flow of water in one direction while preventing any reverse flow, also known as backflow. This function is crucial in plumbing systems to maintain pressure levels and avoid contamination of the water supply. If water were to flow backward, it could potentially carry pollutants or contaminants from one area into the clean supply, which poses health risks. Therefore, a check valve serves as a safeguard against such scenarios by ensuring that once water passes through the valve, it cannot return in the opposite direction.

In contrast, other options such as regulating water temperature or measuring water pressure are not functions of a check valve. These tasks are handled by specific devices like thermostats and pressure gauges, respectively. Furthermore, filtering impurities from water involves the use of filters or purification systems, which are entirely different from the mechanical operation of a check valve. Each of these functions is essential within a plumbing system, but they highlight distinct purposes that separate them from the role of a check valve.