What function does a check valve serve in backflow prevention?

A check valve is specifically designed to prevent the reverse flow of water in a plumbing or water distribution system. By allowing water to flow in only one direction and automatically closing if the flow attempts to reverse, it effectively blocks any potential backflow. This function is crucial in maintaining water quality and ensuring that contaminants from downstream systems do not enter the clean water supply.

In contrast, a check valve does not regulate water temperature, allow flow in both directions, or increase water pressure. These functions are outside of what a check valve is designed to do, making the prevention of backflow its primary and most important role.