What Is Backflow?

Posted on: 15 September 2020

When your plumbing system is being connected, there is a lot of testing that goes into the system. One of the things that the plumbers are going to test is whether or not you have a backflow problem. 


Backflow is the technical name for when water runs backward through the system. For example, if you have a septic system or sewer line, backflow would mean that the liquid that is supposed to run out of your house reverses its flow and then runs back into your house. Backflow can be dangerous because it can taint potable water supplies or cause other damage to your house or building. That's why it is so important to make sure that you have backflow testing done. There are two kinds of backflow that you have to worry about. They are siphonage backflow and backpressure backflow. 

Siphonage Backflow

Siphonage happens as a vacuum process. It happens because something has happened to the incoming water line to cause negative pressure, which is what creates the vacuum. There are a number of things that could cause that negative pressure to happen. For example, if a water main line broke on your street, that would drastically reduce the water pressure on incoming water lines, creating that negative pressure, which could allow the water that should flow out of your house to flow into your house. 

Backpressure Backflow

The other kind of backflow is backpressure backflow. This happens when there is more pressure in the outgoing pipes than in the incoming pipes. As more fluid builds up, the pressure gets higher, which would end up being higher than the incoming pressure, letting everything back up into your pipes and into your house. An example of this would be a clog in your sewer line or a full septic tank. The wastewater can't flow out of your house because of the clog or the full tank, so everything builds up behind that stoppage. More wastewater means more pressure, until not only will nothing go down through the pipes, but everything will also start to come back up through all your drains. 

Making sure that you don't have a backflow problem is important. You don't want to have anything that could cause things like sewage to back up into your house. Having a good backflow test when the plumbing is being connected and then tests any time you are worried can help you be sure that you don't have any issues. 

To learn more, contact a resource that does backflow tests.