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Backflow prevention

What is Backflow?

Backflow is the reversal of the usual direction of water flow in a plumbing system. This can happen when the pressure in the water delivery main is lower than that in the internal plumbing system, a situation known as back siphonage. Back siphonage may occur due to a burst or ruptured water main, or during periods of high demand, such as fire-fighting operations. Backflow can also result from back pressure, which happens when a water pump, like a bore pump, is connected to the internal plumbing system and pumps water at a higher pressure than the mains. If a property’s drinking water supply is accidentally connected to a source of contamination, either through a cross connection or a hose submerged in a container of liquid, pollutants could enter the water supply when there is overpressure on the private property side or a sudden drop in mains pressure.

Backflow prevention devices

Why Should You Install a Backflow Prevention Device?

The community has a right to be protected from water contamination due to a backflow incident. Contaminated water can pose serious health risks, potentially leading to illness or even death. Therefore, there are legal requirements to install a backflow prevention device, as outlined in: Water Services Act 2012 and Water Services Regulations 2013. Given the potentially severe consequences of a backflow incident, we are authorised to issue an order requiring you to install backflow prevention devices at your property boundary, in line with these regulations. Non-compliance may result in penalties of up to $5,000, plus daily fines of $500. Additionally, the regulations empower us to restrict or disconnect water services to safeguard the drinking water supply.

Who Can Install a Backflow Prevention Device?

Only licensed plumbing contractors are authorised to install backflow prevention devices.

When Should I Install a Backflow Prevention Device?
  • If you recently submitted an application through our Land Developers portal for a building development, redevelopment, or modifications to existing water services, your application may have been evaluated for backflow prevention, or your property may have been identified as a potential backflow risk to the public water supply.

The following types of building applications will be reviewed for backflow risk:

  • New developments
  • Redevelopments of existing structures
  • Modifications to any existing water service
  • Additions and alterations (including cases where no water service applications are made, applicable only to properties with existing meters)
  • Multiple residence and/or commercial properties (including those without water service applications, applicable only to properties with existing meters)
  • Any applications involving a fire service
  • Applications where the requested water service size exceeds 25mm (except for fire services, where backflow prevention advice applies regardless of service size)

When your application is approved, you will be informed of the initial backflow risk rating for your property. The final backflow risk level will depend on site-specific activities and, in certain commercial and industrial cases, may default to a high-risk rating.

Backflow Risk Classification

Backflow risk is categorised as low, medium, or high according to AS/NZS 3500.1 standards:

  • Low Risk – Conditions, devices, or practices related to the drinking water supply that may cause a nuisance but do not pose a threat to health or cause injury.
  • Medium Risk – Conditions, devices, or practices connected to the drinking water supply that could potentially harm health.
  • High Risk – Conditions, devices, or practices associated with the drinking water supply that may result in death.
How is the Backflow Risk Rating Determined?
  • Upon the approval of a building development application, redevelopment, or modifications to existing water services, you will be informed of your property’s initial backflow risk rating. This rating determines the type of backflow prevention device required.
  • The final backflow risk rating is influenced by site-specific activities, with certain commercial and industrial operations possibly resulting in a high-risk rating. Fire services are classified as medium risk regardless of size. If you are uncertain about your property’s initial backflow risk rating, consult your builder or developer.
Can I Appeal My Backflow Risk Rating?
  • Yes, if you believe the assigned backflow risk rating is higher than what is appropriate based on the activities at your site, you can appeal the rating. To initiate the appeal, contact our team on 08 9781 0500 or submit an online form via our website https://www.busseltonwater.wa.gov.au/about-us/contact-us/
  • If you decide to appeal, you will need to consult with a qualified licensed plumbing contractor or hydraulic consultant. Your appeal must be submitted within 28 days of receiving the risk rating. We will notify you of the outcome of the review.

Location, installation, ownership & maintenance

Installation of Backflow Prevention Device
  • The backflow prevention device must be installed on your side of the water connection, at the boundary of your property. These devices should not be buried underground, and medium and high-rated devices must not be placed in pits or chambers. The property owner or occupier is responsible for the installation, ongoing testing, and maintenance of the backflow prevention device.
What Should I Do if My Builder Didn’t Install Backflow Prevention?
  • It is the responsibility of the property owner or occupier to ensure that the nominated builder complies with all conditions of the building approval, including the installation of the appropriate backflow prevention device based on the property’s risk rating.
Registration of the Backflow Prevention Device
  • All testable backflow prevention devices (those rated medium or high) installed at the property boundary must be registered. This registration must be submitted to Busselton Water by a licensed plumbing contractor qualified to install these devices, no later than 5 working days after testing is completed.
Backflow Prevention Device Testing and Maintenance
  • Backflow prevention devices installed at the property boundary (including those for high or medium-risk properties and fire services) must be tested at commissioning, after any maintenance, and every 12 months by an accredited tester. We will send reminders to property owners for these boundary devices.
  • While accredited testers may conduct testing, only licensed plumbing contractors are authorised to perform maintenance on backflow devices. Failure to maintain a backflow prevention device may result in a non-compliance notice being issued to the property owner or occupier.
  • Backflow test reports must be submitted online within 5 working days of testing.
  • Please note, we do not manage zone or individual-type backflow prevention devices and do not accept test reports for these devices.

Fire Services

All fire services, regardless of a property’s risk rating, are classified as medium risk and must have at least a medium-rated backflow prevention device installed. Fire services installed before 13 May 2010 are not required to install boundary backflow prevention unless there is an alteration to the fire service at the property boundary.

Reduced water pressure and flow rate

Certain types of backflow prevention devices can lower water pressure and flow rate downstream of the device. If maintaining water pressure and flow rate is essential for activities on your property, it is important to consult with a licensed plumbing contractor or hydraulic consultant before selecting and installing a backflow prevention device.