What is backflow?

Backflow is the unwanted reversal of flow in a water distribution system. Backflow occurs due to backpressure or back-siphonage and allows non-potable substances to enter a public water system through an unprotected cross-connection.

Backpressure occurs when the pressure in a building’s plumbing exceeds the pressure in the water distribution system.

Backsiphonage occurs when there is a partial vacuum (negative pressure) in a water supply system, drawing liquid from the non-potable source into the water distribution system.



You can find more information https://dnr.mo.gov/print/document-search/pub0393

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