What is backflow?
Backflow is a reversal of the normal direction of water flow in a water supply plumbing system. It occurs when the water delivery main is at a lower pressure than the internal plumbing system (back siphonage). Back siphonage can occur when there is a burst or ruptured water main, or due to excessive demand during fire-fighting operations or other periods of high demand.
Backflow can also occur if a water pump, such as a bore pump, is cross connected to the internal water plumbing system, and is pumping bore water at a higher pressure than the water mains pressure (back pressure).
If a property’s drinking water supply is inadvertently connected with a source of pollution, either through a cross connection or simply a hose submerged in a container of liquid, then these pollutants could enter the water supply when there is an overpressure on the private property side or a sudden drop in water mains pressure.
Why install a backflow prevention device?
The community has a right to protection from contaminated water as the result of a backflow incident. Contaminated water can cause health problems or death and because of this, there are obligations under legislation to install a backflow prevention device:
Water Services Act 2012
Water Services Regulations 2013
Because of the potentially serious nature of a backflow incident we can, in accordance with the regulations, serve a notice to you to install backflow devices at your property boundary. These regulations also mean that penalties of up to $5,000 and $500 per day will be issued if you are not compliant.
Under the regulations we also have the power to restrict or disconnect water services to protect the drinking water supply.
Who can install a backflow prevention device?
Only a licensed plumbing contractor may install backflow prevention devices.
When should I install a backflow prevention device?
If you recently applied to us through our BuilderNet® portal for a building development application, redevelopment or changes to existing water services then your application may have been assessed for backflow prevention, or your property has been identified as a backflow risk to the scheme water supply.
The following building application types will be assessed for backflow risk:
- new developments
- redevelopments of existing facilities
- changes to any existing water service
- additions and alterations (includes where no water service applications are included, applicable only if the property has existing meters)
- multiple residence and/or commercial (includes where no water service applications are included, applicable only if the property has existing meters)
- any applications that involve a fire service
- any applications where the minimum water service size applied for is greater than 25mm in size (except fire services, where the backflow advice applies regardless of the service size).
At the time of approval, the applicant will be informed of the property’s initial backflow risk rating. Site-specific activity will determine the final level of backflow risk and for certain commercial and industrial processes may default the property risk rating to high.
New Water Corporation meters 20mm and 25mm in size come with integral dual check valves incorporated within them. This means low risk properties such as residential only; with only metered services (excluding fire services) of this size already have sufficient backflow prevention. Fire services are medium rated regardless of size.
Backflow risk ratings
Backflow risk can be classed as low, medium or high as per AS/NZS 3500.1:2015.
Low risk – any condition, device or practice in connection with the drinking water supply system that constitutes a nuisance but does not endanger health or cause injury.
Medium risk – any condition, device or practice in connection with the drinking water supply system that could endanger health.
High risk – any condition, device or practice in connection with the drinking water supply system that could cause death.
Registration of the backflow prevention device
All backflow prevention devices that are installed at the boundary must be registered. This information should be submitted to Water Corporation by a licensed plumbing contractor qualified to test the devices no later than 5 working days after the test is carried out.
Annual backflow prevention device maintenance
Testable backflow prevention devices at the property boundary must be installed on high or medium risk properties. These legally require testing at commissioning, after any maintenance and every 12 months by a licensed plumbing contractor qualified to test the devices.
We will send a reminder to the property owner for these boundary devices. Failure to maintain a backflow device will result in the serving of a non compliance notice to the property owner or occupier.
Backflow test reports must be submitted online no later than 5 working days after the test is carried out.
We do not manage zone or individual type backflow prevention and does not accept test reports for these types of devices.
Irrespective of the risk rating of a property all fire services are rated medium risk and require (as a minimum) medium rated backflow to be installed.
Fire services that were installed prior to 13 May 2010 are not required to install boundary backflow prevention unless the fire service is being altered at the property boundary.
How we can assist with your back flow needs:
Dynamic Plumbing & Gas can both test and install backflow prevention devices throughout Perth for both water and fire services. Our knowledgable and friendly technicians will ensure your device is checked to be in perfect working order and the required paperwork is lodged with the water corporation. If you need a device installed we can also assist with risk assessment, sizing, positioning and installation.
Get in touch with us today to find out more.