What is a Backflow?

Definition: What Does the Term Backflow Mean?
Reverse direction of fluid flow, from the engineered, intended direction of the flow. This can be an intentional, engineered operation, or an unintended flow of fluid. Normally, if intentional, it is for a cleanout procedure within the piping systems or vessels. Backflow of fluid is a basic engineering term that in hydraulics is usually not a positive situation. Piping systems are normally designed to flow in one direction by the introduction of a mechanical pump pushing the fluid through the system, or by pitching the piping system to ensure that gravity provides the forces required to ensure proper direction of flow. This term, backflow, is especially important, when a piping system is connected to another independent system, that cannot be contaminated, such as the municipal water system of a Town or City. The connections to the municipal system are extremely sensitive to backflow from the secondary piping back into the municipal water systems. Contamination is extremely dangerous, and any possibility of backflow with contamination must be prevented. Sewage backflow is also usually not intended and the replacement of existing sewer lines by contractors in municipalities must be extremely careful of sewage backflow. Severe elevation differences, such as steep roadways, will usually incorporate severe sanitary profiles which present pressure issues at the bottom of the slope. Careful planning and management of sewer line replacement is necessary to prevent the backflow of sewage into residential properties at the bottom of the hill.