Backflow Prevention Durham

At Andrew's plumbing we are fully certified by the Ontario Water Works Association to provide, install and repair all types and sizes of back flow prevention devices. Our plumbers in Durham Region can take care of all makes or models, big or small we do them all.

What is backflow?

Backflow is a flowing back of water or reversal of the normal direction of flow. Backflow may occur due to either back siphonage or back pressure.

What is backpressure?

Back pressure is pressure that is greater than the municipal water system supply pressure. It can happen when there is a connection to a non-potable supply operating at a higher pressure than the water distribution system. Increases in pressure can be created by booster pumps, temperature increases in boilers, interconnections with systems operating at higher pressures and elevated piping (e.g., 30 feet above finished grade).

What causes backflow?

An example is when there is a water main break and the area must be isolated and repaired. When the valves around the repair site are closed, the flow of water is stopped to all points of use such as homes and businesses and begins to flow backwards towards the repair. This is back siphonage and if there are cross connections, contaminants can be drawn into the water system.

Why do backflow prevention devices have to be tested periodically?

Mechanical backflow preventers have internal seats, springs and moving parts that are subject to fouling, wear or fatigue. These mechanical devices and air gaps can also be by-passed. Therefore, some backflow preventers have to be tested periodically to ensure that they are functioning properly and others such as an air gap require a visual check to ensure that they are still in place. The testable backflow preventers must be tested by someone that has had proper training and is qualified to do so. Refer to the training and certification pages for more information on this.