What is the primary purpose of a backflow preventer?

The primary purpose of a backflow preventer is to prevent contamination of the potable water supply. Backflow occurs when the flow of water is reversed, potentially allowing contaminants from a non-potable source to enter the clean water supply system. Backflow preventers are designed to create a barrier that stops this unwanted reverse flow, ensuring that drinking water remains safe and uncontaminated. This is crucial for protecting public health and maintaining the integrity of the water supply system.