TL;DR
A backflow preventer is a mechanical assembly of check valves, and in higher-grade types a relief valve or air inlet, that lets water flow only one direction so contaminated water from irrigation, boilers, fire sprinklers, or hose connections cannot reverse into the potable supply. Reversal happens through backsiphonage when street pressure drops or backpressure when a downstream system pushes harder than the main.
What it means
A backflow preventer is a mechanical assembly of check valves, and in higher-grade types a relief valve or air inlet, that lets water flow only one direction so contaminated water from irrigation, boilers, fire sprinklers, or hose connections cannot reverse into the potable supply. Reversal happens through backsiphonage when street pressure drops or backpressure when a downstream system pushes harder than the main. Types escalate with hazard: hose-bibb vacuum breakers, PVBs, double checks, and RPZ assemblies, certified to standards like ASSE 1013. Testable assemblies require a certified tester annually in most water districts, with the tag wired to the device.
Where it sits in the glossary
Backflow preventer is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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