Backflow Prevention Testing & Installation — Stay Compliant

What Is Backflow and Why Does It Matter?

Backflow occurs when water flows in the wrong direction through a pipe — backwards from your property into the public water main. This can happen when there is a sudden pressure drop in the water main, caused by events such as a water main burst, heavy demand from firefighting operations, or maintenance work by Sydney Water.

If your property has connections that could introduce contaminants into the water supply — think irrigation systems with fertiliser, commercial kitchen equipment, fire hydrant boosters, dental chair water, swimming pool connections or chemical dosing systems — a backflow event could push those contaminants into the drinking water supply serving your neighbours and the broader community.

That is why Sydney Water mandates backflow prevention devices on all properties that present a hazard to the public water supply, and requires annual testing to confirm those devices are working correctly.

Types of Backflow Prevention Devices

Reduced Pressure Zone (RPZ) Device

The RPZ is the highest level of backflow protection and is required for high-hazard applications — chemical plants, medical facilities, mortuaries, commercial laundries and any property using toxic chemicals connected to the water supply. An RPZ device contains two independently acting check valves and a pressure-differential relief valve that dumps water if either check valve fails.

RPZ devices require annual testing and periodic overhaul. They must be installed above ground in an accessible, draining location. Many strata and commercial buildings in the Eastern Suburbs have RPZ devices on their main water supply connection.

Double Check (DC) Valve

Double check valves provide medium-hazard protection and are the most commonly required device for commercial, strata and multi-residential properties. They contain two independently acting check valves in a single body and are available in sizes from 20mm to 150mm.

DC valves are typically installed at the property boundary, near the water meter or at the point of connection for the hazardous service. They require annual testing by an accredited tester.

Dual Check Valve

Dual check valves provide low-hazard protection for residential properties. They are typically installed at the water meter and protect against minor cross-connections such as garden hose attachments and domestic irrigation systems. While not all residential properties require a testable dual check, Sydney Water may mandate one if a hazard assessment identifies a risk.

Backflow Testing — What Is Involved?

Annual backflow testing is a straightforward process that typically takes 15 to 30 minutes per device. Here is what happens:

1. Pre-test inspection. We visually inspect the device for leaks, corrosion, damage and correct installation. We check that the device is accessible, has adequate clearance for maintenance and that test cocks are in good condition.

2. Differential pressure testing. Using a calibrated backflow test kit, we test each check valve and relief valve against the pass/fail criteria specified in AS/NZS 2845.3. The test measures the pressure differential across each component to confirm it is holding within the required tolerance.

3. Pass or fail. If the device passes all tests, we issue a test certificate. If any component fails, we advise on the required repair.

4. Repair or replacement. Common failure modes include worn check valve rubbers, scored relief valve seats and degraded O-rings. We carry repair kits for major brands (Watts, Wilkins, Conbraco, Tyco) and can often complete repairs during the same visit. If the device is beyond economic repair, we replace it with a new unit and retest.

5. Sydney Water lodgement. We submit the completed test report directly to Sydney Water via their online portal. Your property remains compliant, and you have documentation for your records.

Who Needs Backflow Testing in the Eastern Suburbs?

Commercial Properties

All commercial premises connected to Sydney Water’s supply require a backflow prevention device and annual testing. This includes restaurants, cafes, medical practices, dental surgeries, veterinary clinics, laundromats, car washes, hairdressers and any business that uses chemicals or has equipment connected to the water supply.

Strata and Multi-Residential Buildings

Apartment buildings with common property fire services, irrigation systems, swimming pools or centralised hot water plants require backflow prevention on the relevant connections. Many older Eastern Suburbs apartment blocks have had backflow devices retrofitted as part of Sydney Water’s ongoing compliance program.

Schools and Childcare Centres

Educational facilities require backflow protection, particularly on connections to science laboratories, art rooms, irrigation systems and swimming pools.

Residential Properties

While single residential homes do not always require a testable backflow device, Sydney Water may mandate one if your property has fire services, in-ground irrigation with chemical injection, a swimming pool with an automatic fill connected to mains, or any other connection that presents a cross-contamination risk.

The Consequences of Non-Compliance

Sydney Water takes backflow compliance seriously. If your annual test is overdue, you will receive a notice requiring testing within a specified timeframe. Continued non-compliance can result in:

• Restriction or disconnection of your water supply
• Fines under the Sydney Water Act
• Liability for contamination if a backflow event occurs

The annual test is a small investment compared to the risk and disruption of losing your water supply or facing a compliance action.

Our Backflow Testing Service

Mr Plumber provides backflow testing and certification for properties across the entire Eastern Suburbs, including Bondi, Bondi Junction, Randwick, Paddington, Woollahra, Double Bay, Surry Hills, Darlinghurst, Potts Point, Coogee, Maroubra, Kingsford, Mascot and all surrounding suburbs.

We offer:

• Annual reminder service — we contact you when your test is due so you never miss a deadline.
• Same-day repairs — if your device fails, we fix it on the spot where possible.
• Bulk testing rates — discounted pricing for strata buildings and commercial portfolios with multiple devices.
• Sydney Water lodgement — all paperwork handled by us.

Call 1800 247 474 to book your annual backflow test or to arrange installation of a new backflow prevention device.