Resultant Force and Backflow

When there are pressure changes, the pressure of the non-potable source may exceed the pressure of the potable source. This change in pressure is called the Resultant Force and is in the direction of the potable water system. When a resultant force occurs, the action is called Backflow. Backflow is the reversal of flow from one source other than the intended source. It may be freakish and unpredictable. Backflow is produced when there is a change to the pressure between two systems.

Backflow occurs when there is a change in the high normal pressure.  In the normal direction of flow, the high normal pressure becomes the low pressure and the low normal pressure becomes the high pressure.

How would you know that a backflow incident occurred in the distribution system?

Loss of pressure when a spigot or faucet was opened or water discoloration would be an indication that backflow occurred. If no water was coming from the tap this could be an indication that a siphon effect was occurring. If the water was suddenly discolored this could be an indication that the water in the distribution system was flowing against the normal direction of flow.

Any interconnected fluid systems in which the pressure of one excess the pressure of the other may have flow for one to the other because of the pressure differential. The flow will occur from the zone of higher pressure to the zone of lower pressure.