A backflow preventer is a device that helps keep water from flowing backward into a clean water supply. Reverse flow can happen when pressure changes in a plumbing system. The device creates a barrier so water from a connected line is less likely to move into the drinking-water supply.
Why it matters
Different plumbing connections can require different types of backflow protection. Installation, inspection, and testing requirements depend on the system and local rules. A plumber can identify the appropriate protection for a specific connection and check whether it is working as intended.
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