What Is Backflow?
Backflow is the highly unusual circumstance of a reverse flow of water or liquids into the water supply via a cross-connection (a link between potable water and unsafe or unknown sources of water). This process can occur when the water pressure drops and a suction effect occurs, drawing water or liquids the wrong way. A garden hose resting in a backyard puddle, pond, or pool can be a cross-connection. If the water supply pressure were to drop, the water from the puddle, pond, or pool can be suctioned back through the hose and into the drinking water supply in an event called backflow.