What is backflow?
Backflow means the reversal of water flow from the intended direction of flow.
There are two types of backflow -- backpressure backflow and backsiphonage.
Backpressure Backflow - Pressure that is greater than the potable water supply pressure causes backpressure backflow.
Backsiphonage - Occurs when there is a vacuum in a water supply system, which draws the water from the source into a potable water supply. A toilet installed without a toilet ballcock (air gap) will allow water to backflow to other outlets in your house.
If needed, you can install a Backflow Preventer which will prevent water backflow from occurring. Your local plumber will be able to install.