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Backflow Prevention

At G.F. James Plumbing we have a dedicated team of professionally trained Backflow Plumbers. Whether you’re a commercial or residential property, you can be guaranteed our licensed and highly-experienced plumbers will provide you with the best service in RPZ valve installation and backflow assessment.


What is backflow and when is it likely to happen?

Backflow occurs when water from a property flows backwards into council pipes. It’s a possible health risk, due to contaminants that could pollute the water supply.

 Backflow is more likely to occur if: 

There is a drop in the pressure main, e.g. during a main break

Water pressure at the property is higher than at the main, e.g. if a pump is operating on the site.

Backflow prevention devices are need to ensure public water supply isn’t contaminated. All connections to SydneyWater mains must have suitable backlog prevention.


Why do I need a plumber to assess my property’s backflow prevention?

If you have a commercial site with onsite manufacturing or chemical usage it’s necessary in Sydney to have a licensed plumber asses your site and provide you with a report of its specific containment needs

If your plumber determines the site’s hazard rating as low, SydneyWater’s 20 mm and 25 mm water meters are already equipped with an effective backflow prevention device. However, if your property’s water meter is larger than 25 mm, you’ll need to have at least one separate backflow RPZ (Reduced Pressure Zone) valve installed.

Your plumber should also be able to tell you if the device needs annual testing.


Who can install or test a backflow prevention device?

Only accredited backflow plumbers are able to assess your need for a backflow device and install the RPZ valves if necessary. Once a backflow device has been installed on your property, your back flow plumber will need to do a test and follow that up with Sydney Water’s online lodgement system.


Why an RPZ device?

We use the RPZD when there are significant risks to the contamination of Sydney Water’s supply if a hazard were to occur. They’re best suited for their ability to prevent both backflow and back-siphonage, because of their redundant design (it’s able to provide a defence against back flow contamination even if both check valves are compromised) and because they are testable, making yearly checks more convenient.