Backflow Prevention

What is Backflow Prevention work?

Get to know the regulation

Under Part 5 of the Plumbing Regulations 2018, Backflow Prevention work is the repair, alteration, maintenance, testing or commissioning of a backflow prevention device, which is capable of being tested and is listed in Column 1 of Table 4.4.1 of AS/NZS 3500.1.

Typical Backflow Prevention work

Backflow Prevention work protects a property's drinking water supply from contamination that may be caused by backflow. Experienced Backflow prevention plumbers typically do the following work:

  • selecting appropriate backflow prevention devices
  • installing and testing backflow prevention devices
  • maintaining and repairing backflow prevention devices
  • completing required compliance documentation when the backflow device is commissioned.

What do Backflow Prevention plumbers need to know and do?

Plumbers undertaking Backflow Prevention work apply critical knowledge and skills to protect the health and safety of the community. What does this mean for you?
As a registered practitioner, you must be able to understand and apply the compliance requirements of Backflow Prevention work.
These requirements include:

  • AS/NZS 2845.1 – Water Supply – Backflow prevention devices
  • AS/NZS 2845.3, Part 3: Field testing and maintenance of testable devices
  • AS/NZS 3500 National plumbing and drainage.

To undertake Backflow Prevention work to a safe and competent standard, you must also be able to:

  • read a site or building plan and identify water supply lines and locations
  • identify testing and commissioning requirements
  • read, interpret and apply manufacturer specifications for installing backflow prevention devices
  • understand the range of backflow prevention devices available and select those applicable to the hazard rating
  • perform accurate measurements and calculations and document results of work undertaken.

What competencies and experience do you need?

To be registered in Backflow Prevention work you must already be registered in Water Supply work.

The VBA publishes a set of units of competency for each class of plumbing work. Each unit of competency describes a work outcome, all the knowledge and skills needed to do the work to the expected standard, and how the knowledge and skills should be assessed.

The VBA uses the units of competency to assess your skills and experience if you apply to register in a class of plumbing work.

To meet the requirements for registration in Backflow Prevention work, you must:

  • be registered in the class of Water supply work
  • have completed CPCPWT4022A Commission and maintain backflow prevention services, or demonstrate knowledge and competence equivalent to that unit of competence
  • successfully complete the VBA’s examination of registration competencies for Backflow prevention work.

Before applying for registration or licensing, please read the current approved units of competency for Backflow Prevention.

Units of competency for Backflow Prevention work


  • Commission and maintain backflow prevention devices (CPCPWT4022A).


Common units
  • Establish legal and risk management requirements of small business (BSBSMB401A)
  • Carry out work based risk control processes (CPCPCM4011A)
  • Estimate and cost work (CPCPCM4012A)
Class specific
  • Commission and maintain backflow prevention devices (CPCPWT4022A).

How to apply

See: Apply for registration in a specialised or restricted class