Backflow Prevention

Active Plumbing & Drainage is an IQP (Independently Qualified Person) Approved Backflow Technician.

This means that we have a thorough knowledge of backflow prevention and cross connection control, have attended and passed an approved 40-hour Backflow course and have met the pre-requisite standard.

Our Back-Flow tester has:

  • Sat and passed the 40 hour training
  • Up-skilled every 3 years
  • Holds the required insurance levels
  • Operates a certified test gauge
  • Is a current financial member of Water New Zealand

What is Backflow?

Did you know, one of the biggest risks to our water supply is actually backflow? (Read more here) Our water supply is pressurized to allow clean water to flow into public or private premises. Backflow is caused when the water pressure drops in the water distribution system, causing potentially contaminated water from residential or commercial premises to flow back into the public water supply network.

There are 2 types of backflow situations:


Back-siphon can occur when large volumes of water are being drawn from the water supply. This may happen for fire protection; during a water main or plumbing system break; or during a shut down of a water main or plumbing system for repair. During a back-siphon, a reduction of pressure creates a vacuum in the piping and the water is siphoned in the wrong direction.

For example, if a hose tap is open when the end of the hose is submerged in a contaminated container of water, the contaminated water in the container may be siphoned back into the building’s plumbing.


Back-pressure occurs when water is being pumped at a pressure higher than the surrounding town mains or pressure within the building.When back-pressure occurs, water flows in the opposite direction to normal flow.

For example, if a pump supplying water from a non-drinkable source, such as a garden pond, is accidentally connected to the plumbing system, the contaminated water can be pumped back into the drinking water supply. It is important to understand that when coupled with a reduction in mains water pressure, the water source only needs to be slightly elevated above the public water supply pipe pressure to push the water back through the premises into the water mains.

Because the use of chemicals and other potential contaminants is so widespread at both home and in business, backflow can be a major threat to our health, even potentially life threatening, so we all have a responsibility to help reduce this risk.

How to prevent Backflow

To protect our water supply, private property owners have a responsibility to install devices to stop the backflow of water into the public water supply. It is the owner’s responsibility to pay for backflow protection. This is in accordance with:

  • Christchurch City Council Water Related Services Bylaw 2008
  • NZ Building Code
  • Health Act 1956
  • New Zealand Drinking Water Standard.

For homeowners, Christchurch City Council provides low-level protection at the point of connection to the public water supply. It does not protect water from hazards that can occur within the home. If you have a spa bath, swimming pool or dialysis machine, this protection may not be enough.

Businesses, especially those that use chemicals, create a high risk to the water supply and therefore the need for backflow prevention is even greater.

What is the procedure to obtain BackFlow Prevention?

A building consent from the Council must be obtained before any medium or high backflow prevention device(s) can be installed. A suitably qualified person must install backflow prevention devices and an Independently Qualified Person (IQP) on backflow must carry out all testing of the device. (IQPs are registered people who have been recognised as having achieved skills and experience in a particular field.) Finally, a certificate must be sent to the Christchurch City Council for code compliance.

Backflow testing. What are the ongoing requirements?

As part of the installation consent process, you are required to recertify your back flow device annually to ensure compliance. Therefore, every back flow device requires testing every 12 months. At Active Plumbing, we are able to test and recertify your device for you. We provide the local authority test certificate that meets your compliance requirements. If repairs are required, we are able to maintain or repair the device before we certify it for you.

What should you do now?

Call Active Plumbing & Drainage on 0800 367 277 for advice and arrange for an assessment and installation of a Backflow Preventer. We are a Registered IQP Back Flow Prevention Provider and deal with the entire process for you, from submitting the Building Permit through to gaining your Code of Compliance.

Active Plumbing & Drainage, the Canterbury Backflow Specialists

Call us today

021 335 541