Backflow is when water flows backwards into the public water supply network from a private property and is one of the biggest risks to our water supply.
Latest backflow survey and device rollout - Mount Maunganui
Since December 2023, council has been surveying properties by area, prioritising commercial and industrial sites, to assess and ensure compliance with backflow prevention requirements.
We have recently completed surveying commercial properties in Mount Maunganui to ensure that the appropriate backflow prevention devices are fitted. Property owners who require a new device at their property will be contacted via letter in January 2025. Installations will be scheduled directly with each business on-site in February 2025.
Across Aotearoa New Zealand, water is a taonga essential to our wellbeing. We all play a part in protecting our community’s drinking water from potential contamination, and one way we do this is through backflow prevention.
What is backflow?
Backflow happens when water flows backward from a private property into the public water supply. This can contaminate our drinking water, compromising its quality and safety and leading to serious health risks. Backflow can occur from residential, commercial, and industrial properties and can be prevented by installing a backflow prevention device at the property boundary.
How are we keeping our water supply safe?
New Zealand has strict legislation to protect water safety and prevent backflow. The Water Services Act 2021 sets drinking water standards and regulates suppliers. In 2022, Taumata Arowai, the national water regulator, introduced Water Quality Assurance Rules, requiring water suppliers to survey properties every five years to identify risks to the public water supply and ensure proper backflow prevention devices are in place. As a water supplier, Tauranga City Council is legally responsible for protecting its water supply and ensuring that each property complies with this legislation.
For safety and quality assurance, all connections to council water supply must be completed by a council approved contractor. Backflow prevention devices are owned and maintained by council. They are tested annually to ensure the device is functioning and will be maintained and serviced as required.
Backflow prevention surveying
Since 2023, we have been actively surveying all properties that potentially pose a risk to the public water supply network, starting with commercial and industrial properties.
Each survey takes around 30 minutes, during which we check the property to assess what activities are conducted and that the fitted backflow prevention device is suitable. The type of device required depends upon the risk rating assigned to the property.
If the level of protection is not appropriate, we are responsible for ensuring a new device is installed as soon as we practically can. Installation is managed by council and carried out by council contractors, with the full cost for the device and installation invoiced back to the property owner.
Before surveying, we will notify property owners via letter.
What causes backflow?
The two main causes of backflow are:
- When the public water supply network is at a lower pressure than the water pressure on a private property, water will flow backwards into the public water supply network.
- If the public water supply network is directly connected to equipment, which is at a higher pressure, water will be forced back into the public water supply network
Preventing backflow at your property
Since 1997, all new properties in Tauranga must have a backflow prevention device fitted to their water supply. Backflow devices were installed at all other properties throughout the city when new water meters were installed or replaced.
The installation of a backflow prevention device at the point of supply is a condition of supply and is to be fitted before the water supply connection is installed. If other high risk hazards are identified on site, we will advise property owners that a greater level of protection is required.
As a property owner you have a legal obligation to install the appropriate backflow prevention devices to protect the water on your property and ensure you don’t contaminate the public water supply network. Your obligation starts at the water meter and includes your entire property’s water system.
Backflow Prevention, Protecting your Health (415kb pdf)
Backflow risks and solutions
We use the following criteria to determine the level of backflow protection required for boundary protection and the acceptable solution for that risk. It is an approved document from the Building Industry Authority for Water Supplies, G12, Reprinted Incorporating Amendments 1, 2 and 3.
Water Supplies Acceptable Solutions G12/AS1
|
Type of hazard
|
Acceptable devices
|
Backflow prevention standard/industry solution |
|
High
Any condition, device or practice which, in connection with the potable water supply system, has the potential to cause death.
- Autoclaves and sterilisers
- Systems containing chemicals such as anti-freeze, anti-corrosion, biocides, or fungicides
- Beauty salon and hairdresser's sinks
- Boiler, chiller and cooling tower make-up water
- Car and factory washing facilities
- Chemical dispensers
- Chemical injectors
- Chlorinators
- Dental equipment
- Direct heat exchangers
- Fire sprinkler systems and fire hydrant systems that use toxic or hazardous water
- Hose taps associated with High hazard situations like mixing of pesticides
- Irrigation systems with chemicals
- Laboratories
- Mortuaries
- Pest control equipment
- Photography and X-ray machines
- Piers and docks
- Sewage pumps and sump ejectors
- Sluice sinks and bed pan washers
- Livestock water supply with added chemicals
- Veterinary equipment
|
Air gap*
Reduced pressure zone device |
G12/AS1 Figure 1
AS 2845:Pan 1 |
| Note: The examples given are not an exhaustive list. Where there is doubt comparison must be made to the hazard definition. |
|
Medium
Any condition, device or practice which, in connection with the potable water supply system, has the potential to injure or endanger health.
- Appliances, vehicles or equipment
- Auxiliary water supplies such as pumped and non-pumped fire sprinkler secondary water
- Deionised water, reverse osmosis units and equipment cooling without chemicals
- Fire sprinkler systems and building hydrant systems
- Hose taps and fire hose reels associated with Medium hazard
- Irrigation systems with underground controllers
- Irrigation without chemicals
- Livestock water supply without added chemicals
- Untreated water storage tanks
- Water and steam cleaning
- Water for equipment cooling
- Drink dispensers with carbonators
- Swimming pools, spas and fountains.
|
Air gap*
Reduced pressure zone device
Double check valve |
G12/AS1 Figure 1
AS 2845:Part 1
AS 2845:Part 1 |
| Note: The examples given are not an exhaustive list. Where there is doubt comparison must be made to the hazard definitions. |
|
Low
- Hose tap used for fixed domestic irrigation systems
- Facilities used for the storage or preparation of food and beverages
|
Air gap*
Reduced pressure zone device
Double check valve
Hose connection vacuum break |
G12/AS1 Figure 1
AS 2845:Part 1
AS 2845:Part 1
AS 2845:Part 1 |
Source: Building Industry Authority, October 2001
*Air gaps are for internal protection only. Alternative boundary protection must also be installed. (E.g. If risk is ‘medium’, a testable double check backflow prevention device is required).
Not all devices will cover all backflow risks. The below table details what type of device protects from what type of backflow in some given risk situations. Information around what backflow prevention device is appropriate should be advised by a qualified engineer or council.
|
Type of backflow prevention
|
Cross connection hazard
|
| |
HIGH
|
MEDIUM
|
LOW
|
| |
back -pressure |
back-siphonage |
back-pressure |
back-siphonage |
back-pressure |
back-siphonage |
|
Air Gap
(Note 1)
|
X
|
X
|
X
|
X
|
X
|
X
|
| Reduced pressure zone device |
X
|
X
|
X
|
X
|
X
|
X
|
| Double check valve assembly (Note 2) |
|
|
X
|
X
|
X
|
X
|
| Pressure type vacuum breaker(Note 3) |
|
X
|
|
X
|
|
X
|
| Atmospheric vacuum breaker(Note 4) |
|
X
|
|
X
|
|
X
|
|
Note:
- Air gaps must not be installed in a toxic environment, and are for internal protection only. Alternative boundary protection must also be installed.
- Double check valves can be installed in a medium and low hazard toxic environment.
- Pressure type vacuum breakers are designed to vent at 7 kPa or less. However, they require a significantly higher pressure to reseat and must be installed only in systems which provide pressures sufficient to ensure full closing of the valve.
- Hose outlet vacuum breakers are a specific type of atmospheric vacuum breaker.
|
Source: Building Industry Authority, November 2004
Backflow risk categorisation and examples
This list shows typical properties and business in high, medium, and low backflow risk categories. However, it is not exhaustive and may not accurately reflect the actual risk onsite. A risk assessment is required for each property.
| Low Risk: |
Medium Risk: |
High Risk |
| Residential properties (With no pool or spa) |
Properties with Pools or Spas |
Properties with plumbed Bidet systems |
| Retail Stores (Clothing, Electronics, etc.) |
Auto Repair Shops |
Commercial Cleaning Services (e.g Laundromat) |
| Small Offices (with household amenities) |
Manufacturing Workshops |
Restaurants/Bars and Cafes with Commercial Kitchens |
| Places of Worship |
Printing Shops |
Beauty Spas with Specialized Treatments |
| |
Food Preparation Facilities |
Hair dressers (with hair wash basins) |
| |
Pharmacies |
Laboratories |
| |
Butchers |
Dental Clinic |
| |
Bakeries |
Medical Centre |
| |
Restaurants/bars and Cafes (without commercial dishwasher) |
Radiology Studios |
| |
Grocery Stores |
Funeral Homes |
| |
Fitness Centers |
Veterinary Clinics |
| |
Florists |
Pet Grooming Services |
| |
Medium/Large offices (with cafeteria) |
Childcare Facilities incl. Public/Private Schools |
| |
|
Car Wash Facilities |
| |
|
Radiator repairs |
| |
|
Pest Control Services |
| |
|
Manufacturing Plants |
| |
|
Printing and Publishing Services |
| |
|
Garden Supply stores |
Frequently asked questions
The Water Services Act 2021 (WSA) introduced clear and stringent requirements for backflow management. The water services regulator, Taumata Arowai, introduced Water Quality Assurance Rules in 2022 which set out the requirements relating to the performance of drinking water supplier duties under the Act. These rules provide the minimum requirements drinking water suppliers must comply with to demonstrate they are supplying safe drinking water.
These rules came into effect in early 2023 and affect the way council manages backflow prevention assets and processes.
Council must ensure the backflow prevention device at the boundary is appropriate for the level of risk posed by the (activity on the) property. Existing backflow prevention devices that are not adequate could jeopardise the safety of our city’s public water supply network.
The higher the risk rating of potential backflow, the more complex the device that is needed. To ensure the right device is installed for the right risk, a risk rating of high, medium or low will be assessed by council and you will be advised what device you require.
No. A boundary backflow prevention device must be installed by a council approved contractor. Local plumbing companies are not approved to install these.
If, after a backflow risk survey, you are informed you need a new device, the installation will be organised and carried out by council contractors. The full cost of the device and install will be invoiced back to the property owner.
List of council approved contractors
All properties, including council owned facilities, must have an appropriate backflow prevention device installed. Businesses and industries that pose higher risk should consider budgeting for an upgrade however it is the property owner’s responsibility to ensure that an adequate backflow prevention device is installed at the boundary on the water supply connection to protect the public water supply network. The cost of the installation will depend on several factors, such as the size of the connection, the location of the device, and surface conditions at installation site.
Council will allow a minimum of four weeks between surveying a property and installing a replacement backflow prevention device with the invoice to follow installation.
While we strive to provide an accurate estimate, some installations may be more complex, making it difficult to predict the final cost.
We survey all properties that could pose a risk to the public water supply network every five years to ensure the correct backflow prevention device is in place. However, if a high-risk backflow prevention device is currently installed on your property’s water connection at the boundary then you will not be surveyed again. Council tests devices annually and maintains all backflow prevention devices at the boundary.
The cost will depend upon the device required and the complexity of its installation. Costs can range from $3,000 to more than $10,000. You will be advised of a more accurate approximate cost when/if works are required and better understood. The final amount will be invoiced to you the month after the work has been completed.
Yes, pools and spas can pose a backflow risk to the public water supply and require a medium-risk device, specifically a testable double-check backflow prevention device, at the property boundary. It's important to factor this into your budget, as some pool companies may not include it in their quote.
After surveying your property you will receive a call within seven to ten business days and a letter within several weeks.
Once you have had your backflow prevention device installed, it will be vested with council and you don’t have to do anything further. The approved contractor will advise council of the details we need to know. This will be entered into our asset database so that we have a permanent record of it. After installation, council will manage the device and carry out annual testing and maintenance.
Minor maintenance such as the replacement of seals or springs are currently managed and funded by council. In the event that the correct backflow prevention device is installed but has failed its test and is unrepairable, council will install a new one and cover this cost.
Backflow issues can also occur inside your home/property. If you plan any work that alters your plumbing system, it's important to consult a plumber first. Many people unintentionally create cross-connections, putting their own health at risk.
No. This is required by the Water Services Act 2021 (WSA) that introduced clear and stringent requirements for backflow management.
It has been put in place to keep local public water supply networks safe and is not related to the reform or the establishment of new water entities.