What does a backflow preventer do?

A backflow preventer is a critical device in plumbing that specifically serves to protect the potable water supply from contamination. It accomplishes this by preventing the reverse flow of water, which can occur when there is a sudden drop in water pressure in the supply line. This drop can create a vacuum that draws water back from potentially contaminated sources, such as irrigation systems, industrial processes, or even plumbing fixtures that may have been contaminated.

In situations where backflow could occur, the backflow preventer ensures that contaminated water does not enter the clean water system, thereby safeguarding public health. This function is essential in maintaining the quality of drinking water and preventing harmful substances from mixing with the potable water supply.

The other options, such as regulating temperature, enhancing flow rate, or removing sediment, do not accurately describe the primary purpose of a backflow preventer and pertain to different plumbing functions entirely. The distinct role of backflow preventers in ensuring the safety and integrity of the water supply makes option B the correct answer.