Overview
What is backflow prevention?
Backflow is the unwanted reverse flow of water from a property back into the drinking water supply. Under certain pressure conditions — a burst main, high-demand events, or specific site configurations — water from a property's plumbing systems can flow backwards into the mains supply, potentially carrying contaminants with it.
A backflow prevention device creates a mechanical barrier that stops this from happening. Testable devices — including RPZ valves and double check valves — are registered, monitored and require annual compliance testing to confirm they are still functioning.
Why compliance matters
The consequences of a failed or untested backflow device.
A backflow device that has not been tested or that has failed without detection is not providing the protection it is registered to provide. From a property owner's perspective, the consequences of non-compliance are also regulatory — testable devices must be tested annually. If council notices are ignored or testing records cannot be produced, property owners face compliance notices, orders and potential liability.
Property owners
Owner responsibilities for backflow compliance.
If your property has a testable backflow prevention device, the property owner is generally responsible for keeping it accessible, maintained and tested at the required interval — typically every 12 months.
- Arrange annual testing before the due date or notice deadline.
- Keep the device location accessible — overgrown or locked access delays testing.
- Maintain testing and service records — these may be required for council, insurance or sale.
- Act promptly on any failed test — a failed device must be repaired and retested before compliance can be certified.
- Ensure any new devices are registered with the relevant water authority.
Device types
Common testable backflow prevention devices.
RPZ valves
Reduced Pressure Zone valves are used where the risk of contamination is high. Commonly required for commercial, industrial and mixed-use sites with chemical, irrigation or process water risk.
Double check valves
Double check valve assemblies are used for medium-hazard applications — irrigation systems, fire services and some commercial connections.
Other registered assemblies
Other testable backflow prevention assemblies may apply depending on the property, installation type and water authority requirements. GemArk can identify and test devices registered to your property.
Risk examples
Common sources of backflow contamination risk.
Commercial and industrial sites
- Wash bays and vehicle washing facilities
- Chemical dosing and treatment systems
- Manufacturing processes using mains water
- Mechanical and HVAC services
- Cooling towers and process water systems
Property and residential features
- Irrigation and garden watering systems
- Swimming pools and spa connections
- Fire hose reels and sprinkler systems
- Alternative water sources (rainwater, recycled)
- Cafes, food service and hospitality connections
Strata backflow risk
Backflow prevention is a hidden compliance issue in strata buildings.
Strata buildings — particularly mixed-use developments, apartment complexes with common services, and older buildings that have been subdivided — often have backflow prevention devices that are poorly documented, untested, or where responsibility between body corporate and lot owners is unclear.
Read the Smart Strata article
Testing process
How GemArk handles backflow testing.
1. Confirm property and device details
We confirm the address, device type if known, access requirements and any council notice or due date.
2. Test the device
The device is tested to verify functional performance. Visible condition, accessibility and any maintenance issues are noted.
3. Report and certify
You receive clear reporting confirming whether the device passed, failed or requires further action. A compliance certificate is issued and submitted to the relevant authority as required.
FAQ
Common backflow compliance questions.
How often does a backflow device need testing in Brisbane?
Most Brisbane councils require annual testing — every 12 months — by an appropriately endorsed licensed plumber. Results must be reported to the relevant water authority.
What is an RPZ valve and why does it need testing?
An RPZ valve is a mechanical backflow prevention device used where contamination risk is high. RPZ valves can fail over time and require annual testing to verify they are functioning correctly.
What happens if a backflow device fails the test?
If a device fails, the fault must be repaired and the device retested before a compliance certificate can be issued. GemArk reports the outcome clearly so owners know exactly what action is required.
Who is responsible for backflow testing in a strata building?
Responsibility typically sits with the body corporate for shared infrastructure, and with individual owners for devices serving their lot. GemArk can help strata managers and committees understand what testing obligations apply.
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Book backflow testing in Brisbane.
Send the property address, number of known devices, access details and any council notice or due date.
Phone: 0431 502 032
Email: info@gemark.com.au
Contact GemArk