Backflow testing is the yearly check on a testable backflow prevention device, and the report goes to your water authority: Central Coast Council or Hunter Water, depending on where the property is. It catches people out when a reminder notice arrives. Here is what a backflow device does, which properties need one, and what the annual test involves.
TL;DR
Backflow testing checks that a testable backflow device still stops contaminated water flowing back into the drinking supply. Central Coast Council and Hunter Water both require the test at installation and every year after, by an accredited backflow plumber, with the report sent to them. Commercial sites, irrigation, fire services and sites using chemicals are the usual cases. A single low-hazard house on a standard 20 mm or 25 mm service does not need a separate device.
What is backflow, and why does it matter?
Your water is supposed to flow one way: from the main into your taps. Central Coast Council’s backflow prevention page describes backflow as water drawn back into its mains after it has already entered a property’s plumbing. That can happen when pressure drops suddenly after a main breaks, or when a property uses a pump to boost its own pressure. If the water has been near a contamination source, like garden chemicals in an irrigation line, a hose left in a tank or pool, or a cross-connection to recycled or waste water, it can pollute the drinking water everyone shares.
A backflow prevention device stops that. It might be a valve that only allows one-way flow, an air gap that physically separates the two water sources, or a larger assembly for higher-risk sites.
Why does a testable device need a test every year?
Lower-risk situations use non-testable protection that just sits there and works. Medium and high-hazard sites use testable devices, and those are treated differently. Hunter Water notes that backflow devices have internal seals, springs and moving parts that wear or fail, so a device must be tested after installation and every year after by an accredited tester, and registered with Hunter Water. Central Coast Council sets the same rule: an accredited backflow plumber tests medium and high-hazard devices when they are installed and every year afterwards, and the report goes to Council.
Council keeps a register and may send an annual reminder, but getting the test done and the result in on time is the owner’s or occupier’s job. If a device does not comply, Council can issue a notice requiring it to be repaired, tested or replaced.
Hunter Water’s register covers the site containment device, the one straight after the water meter. Zone and individual devices further inside a development are the property owner’s responsibility.
Who actually needs one?
It comes down to the hazard rating, which an accredited backflow plumber assesses on site. Central Coast Council requires a device where the plumber rates the property medium or high hazard. Its examples:
- Commercial and industrial premises, which is the most common case.
- Medical or chemical facilities.
- Irrigation systems connected to the water supply.
- Sites with fire services.
- Properties using chemicals, fertilisers or recycled water.
At home, mention a rainwater tank or bore connected to the drinking water pipework, or a pool with a mains top-up, when the plumber assesses the site. Council counts any connection between drinking water and stored, recycled or waste water as a cross-connection, and water siphoned back from tanks and pools is one of the ways it lists for backflow to contaminate the supply.
A single low-hazard house on a 20 mm or 25 mm service does not need a separate device. Council says so, and Hunter Water’s backflow prevention page notes that its standard 20 mm and 25 mm meters already have a low-hazard device built in. The rating has to be reassessed when what happens on the site changes.
Which device goes with which hazard rating?
Hunter Water sets the device by the hazard rating, using the three ratings in AS/NZS 3500:
| Hazard rating | What it means | Device Hunter Water requires |
|---|---|---|
| Low | A nuisance, but no danger to health | Built into standard 20 mm and 25 mm meters; a testable device after meters larger than 25 mm |
| Medium | Could endanger health | Testable double check valve, straight after the meter |
| High | Could cause death | Testable reduced pressure zone device, straight after the meter |
Where a site runs several processes with different ratings, the highest rating applies.
What does the test involve?
It is a quick job for an accredited tester. We isolate the device, connect a test kit, check that the valve and its non-return mechanism hold pressure the way they are meant to, and record the readings. If it passes, we issue the certificate and lodge it with the water authority so your record stays current. If it fails, the device usually needs a service or a part, which we can sort, and then we retest.
Donza Plumbing installs, repairs and carries out the annual test and certification on testable devices. If you have had a reminder, or you are not sure whether your property needs one, request a callback or see our backflow prevention service. For Hunter Water properties, there is a page on backflow testing in Lake Macquarie.