Written by JSW Plumbing | Published on June 2025
In NSW, backflow prevention devices must be tested at least once every 12 months by a licensed plumber who holds a backflow prevention endorsement. This annual testing requirement is set by your local water authority and applies to any property with a registered backflow prevention device.
This article covers why annual testing is mandatory, what the testing process involves, who is responsible, and what happens if you miss a test. If you are in Thornleigh, Hornsby, or anywhere in the Hills District, JSW Plumbing can take care of your annual compliance testing.
Understand Why Annual Backflow Testing Is Required in NSW
Backflow prevention devices protect the public drinking water supply from contamination. When water pressure drops suddenly, water can flow backwards through pipes and pull pollutants, chemicals, or bacteria into the mains supply.
NSW water authorities classify backflow risk into hazard levels. Higher hazard properties, such as medical facilities, irrigation systems, and industrial sites, are required to have more robust devices tested regularly.
The annual testing requirement exists because backflow prevention valves can fail silently. A device may look fine from the outside but be non-functional internally. Only a pressure test confirms it is working correctly.
Sydney Water and Hunter Water both mandate annual testing under their Customer Contract and the NSW Code of Practice for Plumbing and Drainage. Failing to test is a compliance breach that can result in fines or water supply disconnection.
Identify Which Properties Need Backflow Testing
Not every property in NSW has a registered backflow prevention device, but many do. If you have one, annual testing is compulsory regardless of the property type.
Common properties that require backflow testing include:
- Commercial and retail premises with irrigation systems
- Medical, dental, and veterinary clinics
- Industrial and manufacturing sites
- Restaurants, cafes, and food processing facilities
- Schools and childcare centres
- Residential properties with a registered high-hazard device
- Apartment buildings with a master meter and backflow device
- Properties with swimming pools connected to mains water
In the Hornsby and Hills District area, properties with large gardens and in-ground irrigation are common triggers for backflow device registration. If you are unsure whether your property has a registered device, check your water authority records or ask JSW Plumbing to investigate.
Review the Types of Backflow Prevention Devices Tested
Different hazard levels require different devices. The type installed on your property determines the complexity and cost of the test. Here is a breakdown of common devices and their typical application.
| Device Type | Hazard Level | Typical Application |
|---|---|---|
| Reduced Pressure Zone (RPZ) Valve | High | Industrial, medical, chemical sites |
| Double Check Valve (DCV) | Medium | Commercial irrigation, fire systems |
| Dual Check Valve (DCkV) | Low | Residential, low-risk commercial |
| Pressure Vacuum Breaker (PVB) | Medium | Outdoor irrigation above grade |
| Atmospheric Vacuum Breaker (AVB) | Low to Medium | Hose taps, garden connections |
RPZ valves are the most commonly tested device in commercial properties around Thornleigh and the Hills District. They require a full differential pressure test using calibrated gauges to confirm each relief and check valve is operating within tolerance.
Understand What Happens During a Backflow Test
A backflow test is not a visual inspection. It is a functional pressure test carried out with calibrated differential pressure gauges. The process is straightforward but must be done by a licensed plumber with a backflow endorsement.
Here is what to expect during a standard backflow test:
- The plumber shuts off downstream water supply to the device.
- Calibrated test equipment is connected to the test ports on the device.
- Each check valve and the relief valve are tested independently for correct pressure differential and seating.
- Results are recorded on an official test report form.
- If the device passes, a compliance certificate is issued.
- If it fails, the device is repaired or replaced before a retest is conducted.
- Test results are submitted to the relevant water authority.
A typical backflow test takes between 30 and 60 minutes for a single device. Properties with multiple devices will take longer. JSW Plumbing carries calibrated test equipment on all service vehicles to complete testing efficiently with minimal disruption to your water supply.
Compare Backflow Testing Costs in the Hills District and Hornsby Area
Backflow testing costs in NSW vary depending on the device type, property size, and whether any repairs are needed. The table below gives a general guide for the Hills District and Hornsby region.
| Service | Estimated Cost (AUD) | Notes |
|---|---|---|
| Standard RPZ valve test (1 device) | $150 to $250 | Includes test report and submission |
| Double check valve test | $120 to $200 | Single device, standard access |
| Multiple device test (per device) | $100 to $180 | Reduced rate for multiple units |
| RPZ valve service and retest | $250 to $450 | If internal components need replacement |
| Full RPZ valve replacement | $600 to $1,200+ | Depends on valve size and brand |
These are general estimates. Prices vary based on access difficulty, valve size, and whether the property is commercial or residential. Brands like Watts, Febco, and Ames are common in this region. Genuine replacement parts for these brands are readily available through local suppliers in the Hills District.
Always request an itemised quote before work begins. JSW Plumbing provides upfront pricing so there are no surprises on the invoice.
Know Who Is Responsible for Organising Backflow Testing
The property owner is legally responsible for ensuring annual backflow testing is carried out and that records are submitted to the water authority on time. This responsibility cannot be transferred to a tenant unless it is clearly written into the lease agreement.
For strata buildings in areas like Thornleigh and Hornsby, the owners corporation is typically responsible for the master meter backflow device. Individual lot owners may be responsible for devices serving their specific tenancy.
Key responsibilities include:
- Engaging a licensed plumber with a backflow endorsement each year
- Keeping records of all test results and certificates for at least three years
- Ensuring failed devices are repaired and retested promptly
- Notifying the water authority if a device is decommissioned or relocated
- Responding to any compliance notices from Sydney Water or Hunter Water within the required timeframe
If you own a commercial property or strata complex and are not sure who manages your backflow compliance, contact your water authority or speak with a licensed plumber directly. Missing a test cycle can lead to formal notices and additional costs.
FAQs on Backflow Prevention Device Testing in NSW
What happens if I miss the annual backflow test deadline?
If you miss your annual test, your water authority can issue a formal compliance notice. Continued non-compliance may result in fines or, in serious cases, suspension of your water supply connection. It is best to schedule the test before the due date rather than waiting for a reminder.
Can any licensed plumber test a backflow prevention device in NSW?
No. The plumber must hold a backflow prevention endorsement in addition to their general plumbing licence. This endorsement confirms they have specific training in testing procedures and use of calibrated differential pressure gauges. Always confirm the plumber holds this endorsement before booking.
How do I find out if my property has a registered backflow device?
You can contact Sydney Water or your local water authority and request a search of your property’s records. Alternatively, a licensed plumber can inspect your meter and internal plumbing to identify any installed devices. JSW Plumbing can assist with this inspection for properties in the Hornsby and Hills District area.
Does a residential property need backflow testing in NSW?
Most standard residential properties do not have a registered high-hazard device. However, if your home has an in-ground irrigation system connected to mains water, or a pool auto-fill connected without an air gap, a device may have been installed and registered. Check with your water authority to confirm your property’s status.
What is the difference between a backflow test and a backflow service?
A test confirms whether the device is functioning within required pressure tolerances. A service involves cleaning, replacing internal components like seals and check valves, and retesting. If a device fails its annual test, a service or repair is required before it can be certified as compliant.
How long does it take to get a backflow test certificate after testing?
If the device passes the test, the certificate is usually issued on the same day or within 24 to 48 hours. The plumber is also responsible for submitting results to the water authority, so you do not need to do this yourself. Keep a copy of your certificate for your own records.
Wrap Up and Next Steps
Backflow prevention devices in NSW must be tested every 12 months by a licensed plumber with a backflow endorsement. The property owner is responsible for organising the test, keeping records, and submitting results to the water authority on time.
If your annual test is coming up, or you are not sure whether your property has a registered device, JSW Plumbing can help. We service properties across Thornleigh, Hornsby, and the wider Hills District with qualified, endorsed plumbers and same-day test certificates.
Call JSW Plumbing today to book your backflow test or to ask any questions about your compliance obligations. We make the process straightforward and take care of all the paperwork for you.
