What is backflow? Developments, redevelopments and changed services
Backflow prevention: What is backflow? New developments, redevelopments and changed services, Backflow Prevention Policy, Backflow prevention deviceBackflow Regulations and Standards, Ongoing backflow device maintenance.Subject: Plumbing - Sub Subject: Backflow Prevention
Date: 6/23/2019 Status: ACTIVE
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❝What is backflow? Developments, redevelopments and changed services❞ answers. technician asked first. Total 5 replies.
Backflow preventionAn ongoing threat to the quality of Water Corporation’s drinking water supply is the
flow of water backwards from a customer's property through their property's water service connection (fire services included). This water may be contaminated by the activities within the property, and may cause death, health problems or an inconvenience to persons ingesting or using the water.
What is backflow?Backflow is the 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 (backsiphonage). Backsiphonage can occur when there is a burst or ruptured water main, or when there are periods of high demand. Excessive demand during fire fighting operations can also result in backsiphonage.
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 (backpressure).
If a property’s drinking water supply is inadvertently interconnected 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.
Backflow Prevention PolicyWater Corporation’s Backflow Prevention Policy requires the installation of approved backflow prevention containment devices at the boundary of every water service connection to a property (including fire services). At this point, fire services that were installed prior to May 2010, are not required to install a boundary device unless the fire service is being altered at the property boundary. This policy is supported by relevant legislation and plumbing standards.
New developments, redevelopments and changed servicesAt the time of building approval, development application, redevelopment or changes to existing water services, the applicant will be informed of the property’s risk rating.
The following building application types will be assessed for backflow risk:
- New developments
- Redevelopments of existing facilities
- Changes to any existing water service
- Additions/alterations (including 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 and 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)
- Building application approvals also include:A backflow approval sticker as part of the approved site plan document
- The applicable backflow information sheet (directed towards the applicant), based on the assessed backflow risk (high, medium or low) and
- Plumber’s information sheet (designed for the applicant to provide to their nominated licensed plumbing contractor and/or hydraulics consultant).
If a property owner considers the risk rating assigned to their property is higher than the risk of activities being carried out, then the property owner may appeal this rating.
- The risk rating of a property determines the minimum requirement for the type of backflow prevention device(s).
- Irrespective of the risk rating of a property, all fire services are rated medium risk and require (as a minimum) a medium rated device to be installed.
- If the future land use is unknown, the risk rating will default to high.
- Where there is mixed use on a property, the risk rating will default to high.
- Changes in the activities within a property can result in a change of the backflow risk rating and the backflow device(s) required.
Backflow prevention deviceThe containment backflow prevention device must be installed on the customer’s side of the water connection at the property boundary, and belongs to the owner of the property.
The installation of a containment backflow prevention device does not eliminate the need for zone and individual backflow prevention devices that may be required under plumbing standards. Water Corporation does not manage zone or individual backflow protection.
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.
• Boundary containment backflow preventiondevices are required to be installed as part of the plumbing system downstream, and as close as practicable to the property’s water meter (or property boundary if no water meter is available). Refer to the Appendix on page 44.
• No connections are permitted between the meter outlet and the containment device.
• If continuity of supply is critical to your client, consideration should be given to connecting duplicate devices in parallel.
• If the property has more than one water service, you will need to install a device/s at the connection point for each of those services.
• All fire services are rated as medium risk, and the installation of a medium risk rated device is required, as a minimum (excludes fires services installed prior to May 2010).
• The installation of some forms of backflow prevention devices will reduce water pressure/ flow rate downstream of the device. If the water pressure and/or flow rate is critical to your client, then this should be discussed with your client prior to choosing and installing the final backflow prevention device.
Work related to the installation of backflow devices is identified as plumbing work and is therefore covered by the Plumbing Regulations. Compliance with the plumbing standards will therefore be monitored by the PLB you are required to notify the PLB of your intention to carry out the work.
Only licensed plumbers who are qualified to install, test and certify backflow prevention devices are permitted to carry out such works.
Water Corporation will inspect properties to ensure ongoing compliance with its Backflow Prevention Policy.
Backflow Regulations and Standards
Water Corporation requirements relating to the installation, maintenance and testing of a backflow prevention device are supported by legislation and plumbing standards.
The requirement to have and maintain backflow prevention devices at the boundary of a property is supported by legislation, including the following regulations:
• Regulations 42 and 43 Water Services Regulations 2013
Due to the potentially serious nature of a backflow incident, Water Corporation can in accordance with these regulations serve an order on a property owner or occupier to install backflow devices.
The regulations also provide for penalties for non-compliance under the Water Services Act 2012 (WA). Water Corporation has the power to restrict or disconnect water services, to protect the drinking water supply from potential contamination caused by a backflow event from a property.
Standards for backflow prevention
In addition to all plumbing regulations, licensed plumbing contractors must also apply the following standards for backflow prevention:
- AS/NZS 3500:2015 Plumbing and Drainage Part 1: Water Services.
- AS/NZS 2845:2010 Water Supply-Backflow Prevention Devices Part 1: Materials, design and performance requirements.
- AS 2845:2010 Water Supply-Backflow Prevention Devices Part 2: Air gaps and break tanks.
- AS 2845:2010 Water Supply-Backflow Prevention Devices Part 3: Field testing and maintenance.
Ongoing backflow device maintenanceTestable backflow prevention devices at the property boundary must be installed on high or medium risk properties. These require testing:
• At commissioning, after any maintenance and Every 12 months by a licensed plumbing contractor, permitted to test the devices.
Water Corporation will send an annual reminder letter 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 to Water Corporation no later than 5 working days after the test is carried out.
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