How Often is Backflow Testing Required

What is Backflow Testing?

A backflow test checks your plumbing system to ensure water flows in one direction and that the water from your taps is clean.

When backflow occurs, clean drinking water can mix with contaminated water, making the supply unsafe to use. A backflow test checks that your backflow prevention device is still doing its job and keeping the water supply protected.

What Causes Backflow?

Backflow generally happens for two reasons: back siphonage and backpressure.

Back siphonage occurs when there is a sudden drop in water pressure. This change in pressure can cause water to move backwards instead of forward, pulling contaminated water into the clean supply.

A common example in a residential home is a garden hose left submerged in a bucket or attached to a spray bottle. If the pressure drops, the water in the hose can be sucked back into the main supply.

Backpressure happens when the pressure from a connected water source becomes greater than the pressure of the main water supply. This pushes contaminated water back into the system.

For example, a blocked pipe or a boiler without proper venting can create enough pressure to force water backwards.

Factors that may influence testing frequency

Backflow testing requirements are not the same for every property. The following things can change how often testing is needed:

Some councils will update a property’s risk rating over time, which can affect how often testing must be done.

How Often is Testing Needed?

How often you need to test your backflow prevention device depends mainly on the type of property and the rules set by your local water authority. In most parts of Australia, annual backflow testing is required for any property that has a testable backflow prevention device. This applies to both residential and commercial properties that fall under a medium or high risk rating.

Commercial and industrial sites usually have stricter rules. Places like:

are treated as higher-risk properties. Because of this, they must complete yearly testing to stay compliant, and some councils may require even more frequent checks.

For homeowners, annual testing may not always be legally enforced, but it is still strongly recommended. It ensures the device is working correctly and keeps drinking water safe.
Staying compliant usually means using a licensed backflow plumber who can test the device, complete the paperwork and submit the results to the local water authority.