Most Melbourne homeowners have never heard of backflow — until they receive a notice from their water authority. But understanding backflow prevention is important for your family’s health and for staying compliant with Victorian regulations.

What Is Backflow?

Backflow happens when water flows in the wrong direction through your plumbing system. Instead of clean water flowing from the mains into your home, contaminated water flows backwards into the drinking water supply.

This can introduce:

• Bacteria and viruses from sewage
• Chemicals from garden irrigation systems
• Pesticides and fertilisers from lawn sprinkler systems
• Heavy metals from industrial processes
• Stagnant water harbouring harmful organisms

How Does Backflow Happen?

Two main causes:

Back Pressure

When pressure in your plumbing system exceeds the mains water pressure, pushing water backwards. This can happen with:

• Boilers and hot water systems
• Pumps connected to the water supply
• Elevated storage tanks

Back Siphonage

When mains pressure drops suddenly (from a water main break or high demand), creating a vacuum that sucks water backwards. This can happen during:

• Water main repairs in your street
• Fire hydrant use nearby
• Peak demand periods

Do You Need a Backflow Prevention Device?

In Victoria, backflow prevention is required for properties with:

• Irrigation systems - Garden sprinklers and drip systems
• Swimming pools and spas - Any connection to the water supply
• Fire hose reels and sprinkler systems - Commercial and some residential
• Rainwater tanks connected to mains water
• Any cross-connection between potable and non-potable water

Even if you’re not sure, your water authority (Yarra Valley Water, South East Water, or City West Water) can advise on what’s required for your property.

Types of Backflow Prevention Devices

Testable Devices

Reduced Pressure Zone Device (RPZD)

• Highest level of protection
• Required for high-hazard connections
• Must be tested annually by a licensed plumber

Double Check Valve Assembly (DCVA)

• Medium level of protection
• Common for residential irrigation systems
• Must be tested annually

Non-Testable Devices

Dual Check Valve

• Basic protection for low-hazard connections
• Installed at the water meter
• Doesn’t require annual testing

Atmospheric Vacuum Breaker

• Prevents back siphonage only
• Common on garden taps and hose connections

Annual Testing Requirements

In Victoria, testable backflow prevention devices must be tested annually by a licensed plumber. This is a legal requirement, not optional.

What happens during testing:

1. The plumber tests the device using calibrated equipment
2. Results are recorded on an official test report
3. The report is submitted to your water authority
4. Any faulty devices are repaired or replaced

What Happens If You Don’t Comply?

Your water authority can:

• Send repeated compliance notices
• Restrict or disconnect your water supply
• Issue fines
• Hold you liable for any contamination events

Is Backflow Prevention Expensive?

The cost of backflow prevention depends on the type of device required and the complexity of your installation. However, the investment is small compared to the health risks and potential penalties for non-compliance. Contact us for a quote specific to your property.

Hankook Plumbing Backflow Services

We provide complete backflow prevention services across Melbourne’s eastern suburbs:

• Installation of all backflow device types
• Annual testing with reports submitted to your water authority
• Repairs and replacement of faulty devices
• Compliance advice — we’ll tell you exactly what your property needs

Stay compliant and keep your water safe. Call Hankook Plumbing on 0407 756 172 to book your backflow test or installation.