What is the main purpose of a backflow preventer?

The main purpose of a backflow preventer is to prevent contamination of potable water. Backflow is the undesirable reversal of flow in a piping system, which can occur due to changes in pressure and can lead to contaminated water being siphoned or pushed back into the clean water supply. A backflow preventer is designed specifically to ensure that water can only flow in one direction, effectively blocking any potential contaminants from entering the potable water system. This is crucial for maintaining the safety and quality of drinking water, adhering to health regulations, and protecting public health.

The other options, while related to water systems, do not accurately describe the function of a backflow preventer. Increasing water pressure or maintaining consistent water levels pertains more to pumps or pressure regulators. Filtering impurities from drinking water refers to water filtration systems that eventually serve a different purpose focused on cleaning rather than preventing backflow.