Backflow Prevention

Clyne & Bennie Plumbing can offer a full site survey to determine your backflow requirements. On completion of the survey we can provide a free quote to supply and install any required devices, including processing the required building consents.

  • Survey
  • Design
  • Consent (from council)
  • Installation 
  • Testing
  • Maintaining

Backflow Prevention

IQP - backflow testing and survey

Water contamination has become an area of concern for councils and building owners. A number of simple devices are available that guarantee that water can only pass through a pipeline in one direction. The type of device recommended depends on the type of activity being carried out on the private water supply system and whether the risk of contamination is assessed as high, medium or low.

What is backflow?

Backflow can occur when the water supply pressure at a private property is greater than the mains water pressure in the public water supply system and water flows backwards along a private pipe to the public water supply. There are three main types of backflow:



Back siphonage

Siphonage occurs when a temporary drop in water pressure occurs and water is siphoned into the mains water pipeline, e.g. when a contractor is carrying out a repair to a water supply main at the same time as a property owner in the area is filling a swimming pool with a hose. The chlorinated swimming pool water may inadvertently be siphoned into the mains water supply system and contaminate the public water supply.


This occurs when pressure in the private water supply is greater than the actual mains pressure and water is forced back into the mains water supply system.

Cross connection

This can occur when there is any potential or actual connection between a potable water supply and a source of contamination. The most common cross-connection is the humble garden hose, which could be left in a sump or swimming pool. The hose does not necessarily have to be in contact with a hazard to require a backflow preventative to be installed. If there is potential for the hose to come in contact with a hazard, a backflow preventative must be installed.


Backflow can result in contamination of our public water supply and affect the quality of water you receive.

Annual testing and repairs:

It is a requirement as part of the building warrant of fitness (WOF) that the testable devices are tested annually by an independently qualified person (IQP).

Clyne & Bennie Plumbing is registered as an IQP and has staff that can test and service any brand of valve. On completion, the valves are tagged and a BA12A is provided to the client. This assists our clients to complete their annual building WOF with the city council.

Do you have a building that needs an annual test carried out? Contact us now to pre-book for your next test. We will set up your testing and document your system to ensure all the devices are included.


For further information on our range please enquire here.