What Is A Backflow Prevention Device
Maintaining a clean and reliable water supply is a fundamental public health requirement. One essential yet often overlooked component of a safe plumbing system is the backflow prevention device. These devices are designed to stop contaminated water from flowing back into potable water systems. In this article, we explore what a backflow prevention device is, its function, types, installation requirements, and regulatory importance in Australia.
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Understanding Backflow
Backflow refers to the undesirable reverse flow of water or other substances into the clean water supply. It can occur in any plumbing system and has the potential to introduce contaminants such as chemicals, fertilisers, human waste, or bacteria into otherwise safe drinking water.
There are two main causes of backflow:
- Back Siphonage: This happens when the water pressure in the main supply line drops suddenly—such as during firefighting or a water main break. The drop in pressure creates a vacuum that can draw non-potable substances into the potable supply.
- Back Pressure: This occurs when a connected system (e.g., a boiler or irrigation system) has higher pressure than the incoming water supply, forcing used or contaminated water to flow back into the clean supply.
Both scenarios pose a risk to health and safety, especially in environments like hospitals, commercial kitchens, or industrial sites. Recognising how and why backflow occurs is the first step in understanding what is a backflow prevention device and why it matters.
Purpose of Backflow Prevention Devices
A backflow prevention device is specifically engineered to stop the reverse flow of water. It acts as a physical barrier, allowing water to flow in only one direction—into your building or system—and preventing any return flow.
These devices are critical for:
- Protecting public water supply systems from contaminants introduced by private properties.
- Ensuring legal compliance with plumbing and environmental regulations.
- Mitigating risks associated with chemical or biological pollutants.
- Preventing financial liability in the event of contamination incidents.
Understanding what is a backflow prevention device involves recognising its role as both a safety measure and a regulatory requirement. They are commonly used in high-risk environments, including commercial food preparation areas, medical laboratories, fire services, and large irrigation systems.
Types of Backflow Prevention Devices
There are several types of backflow prevention devices available, each designed for specific applications and hazard levels:
1. Air Gaps
An air gap is the most effective and simplest form of backflow prevention. It involves creating a physical space between the water outlet and any potentially contaminated source. Common in kitchen sinks and industrial wash stations, it ensures contaminated water cannot be siphoned back.
2. Atmospheric Vacuum Breaker (AVB)
Typically installed on taps and garden hose connections, an AVB prevents back siphonage by introducing air into the system when the pressure drops, stopping contaminated water from re-entering the supply.
3. Double Check Valve Assembly (DCVA)
Used in low to medium-hazard situations, such as in residential fire systems or sprinkler systems. The DCVA has two independently acting check valves, offering redundancy in case one fails.
4. Reduced Pressure Zone Device (RPZD)
Designed for high-hazard environments, the RPZD includes two check valves and a relief valve. It is the most reliable device where there is a serious risk of contamination from toxic substances.
5. Pressure Vacuum Breaker (PVB)
Commonly used in irrigation systems, the PVB allows air to enter the system to prevent back siphonage when pressure drops. It must be installed above the highest point in the system.
Each of these options must be selected based on the level of risk present at the installation site. Knowing what is a backflow prevention device means understanding that the wrong device in a high-risk environment could result in system failure and serious health risks.
Regulatory Standards in Australia
Australia has strict codes and standards that govern the use and maintenance of backflow prevention devices. These are primarily outlined in the Plumbing Code of Australia (PCA) and AS/NZS 3500 standards.
Key regulations include:
- Properties must be assessed for low, medium, or high backflow risk.
- Mandatory installation of compliant backflow devices for certain property types and water systems.
- Annual testing requirements for medium and high-risk devices.
- Compliance certificates must be submitted to local water authorities after each test or installation.
Only licensed plumbers certified in backflow prevention are allowed to carry out installation and testing. These regulatory measures are in place to ensure that the devices perform as intended and that the public water supply is adequately protected.
Installation and Maintenance Requirements
Installation of a backflow prevention device must follow a risk-based approach. The process typically involves:
Site Assessment
A licensed plumber assesses the potential risks at the site, determining the level of hazard involved and the most appropriate device for the application.
Device Selection and Positioning
Correct selection is crucial. Devices must be approved for use in Australia and installed in locations that are accessible for testing and maintenance. Placement should avoid areas where the device might freeze or be submerged.
Annual Maintenance and Testing
Devices, especially those in high-risk areas, degrade over time due to wear, pressure changes, and environmental conditions. Australian law requires:
- Annual testing by a licensed backflow technician
- Record submission to local water authorities
- Immediate repairs or replacements if the device fails
Understanding what is a backflow prevention device also includes acknowledging that these are not “set and forget” components—they require ongoing oversight to function properly.
Common Applications and Hazard Ratings
Backflow devices are installed across a wide range of settings based on the hazard level:
- Low Hazard: Garden irrigation systems without fertilisers, residential outdoor taps
- Medium Hazard: Commercial laundry equipment, hair salons, residential fire systems
- High Hazard: Chemical plants, medical clinics, industrial kitchens, agricultural spray systems
Examples of where you’ll find backflow prevention devices in use include:
- Commercial buildings with multiple water entry points
- Apartment complexes
- Swimming pools with automatic top-up systems
- Car wash bays
- Fire hose reels and hydrants
Correctly matching the device to the hazard level is essential for both safety and compliance.`
Importance of Regular Testing
While installation is critical, regular testing is what guarantees long-term protection. Faulty valves, wear-and-tear, debris build-up, and corrosion can cause devices to malfunction.
Why Annual Testing Matters:
- Prevents system failures due to undetected faults
- Ensures compliance with council and water authority requirements
- Validates device functionality in emergency situations (e.g. fire hose use)
- Reduces the risk of penalties or loss of insurance coverage
Testing involves checking the operation of each component, verifying pressure differentials, and recording results in compliance logs. Only certified testers can issue valid test results.
Responsibilities of Property Owners
Property owners—both residential and commercial—are legally responsible for ensuring backflow devices on their property are installed, tested, and maintained.
Owner obligations include:
- Engaging licensed plumbers for all installation and testing
- Maintaining accurate test records
- Replacing failed or expired devices immediately
- Submitting reports to the relevant water authority
Failure to fulfil these responsibilities can result in fines, disconnection of water supply, or liability in the event of a contamination incident. Knowing what is a backflow prevention device also means knowing your obligations in managing it.
Ensure Safe Water Supply with Professional Backflow Prevention Services
Professional support is essential when it comes to safeguarding your water supply. Burren Plumbing offers certified backflow prevention services across Australia, including:
- Risk assessments for residential and commercial properties
- Installation of all approved backflow prevention devices
- Annual testing, certification, and compliance reporting
- Prompt repairs and replacements when necessary
Whether you’re a property manager, business owner, or homeowner, ensuring your water system is protected against backflow is both a legal requirement and a practical necessity.
Contact Burren Plumbing today to schedule an inspection or annual backflow test. Their licensed technicians understand what is a backflow prevention device, how it should be installed, and how to keep it running reliably all year round.
Contact us with confidence. We have over 16 years experience in the plumbing trade, are fully licensed (Lic: 263313C) and have public liability insurance. We treat your home with care and promise to leave it in the same state as when we arrived.
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