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New rules to manage the backflow risks in drinking water


8 Sep 2021

The key message to conference attendees is that Taumata Arowai will be taking an interest in backflow and, under the new rules, every water supplier will have a responsibility to assess the risk of backflow to their network and ensure backflow prevention devices are installed where they are needed.

To balance this we will make sure that there is adequate time to understand and respond to the new rules.

What is backflow?

Backflow occurs when contaminated or dirty water is sucked back into the drinking water network from pipes, taps or outlets. When the pressure drops in the mains nearby, it can suck liquid back into the network from connections to houses or businesses. This could be through a hose sitting in a tank of chemicals, an irrigation outlet lying in a puddle of fertiliser, or countless other sources.

If the outlet is connected to the mains, it is vulnerable to backflow, unless a backflow prevention device is installed.

Backflow is a serious and growing risk to the safety of drinking water supplies

The Government estimates that at least 34,000 people become sick every year from their drinking water, and evidence suggests that at least a third of these cases can be traced back to problems in the drinking water network rather than source water.

Backflow is known to be a major contributor to these network issues.

There have been situations where caustic soda, pool water, and even beer has contaminated drinking water networks through backflow.

By requiring water suppliers to better understand risks in their networks, we will be able to ensure appropriate backflow devices are installed where they are needed.

The proposed new rules represent a significant shift to a more proactive approach to identifying risks in drinking water risk management.

The essence of this shift is to place full responsibility for delivering safe drinking water in the hands of water suppliers. If you are providing drinking water, you have a duty of care to make sure it meets the standards and is safe for consumers to drink. This means taking a proactive approach to identifying risks rather than waiting for something to go wrong to introduce safety measures.

Under the proposed new rules, all water suppliers will be expected to assess the risk of backflow in their supply network and to prevent its occurrence.

For small supplies serving fewer than 50 people, the rule is simple: A backflow prevention device must be fitted where there is a medium or high risk of backflow.

For small supplies, serving between 50 to 500 people, the rules are a little more complex. They require the water supplier to undertake an assessment of their network for backflow risks each year including a record of where backflow risks exist. They will need to ensure suitable backflow devices are installed where they are needed and show that all testable backflow devices have been tested annually by a trained and qualified person.

The rules for large supplies, serving over 500 people, are more comprehensive. Large suppliers will need to:

  • Prepare and implement a backflow prevention programme.
  • Survey their customers’ premises at least every five years to assess backflow risks.
  • Recommend to customers which backflow prevention devices they need and make sure they are installed within a reasonable timeframe.
  • Test all backflow prevention devices annually.
  • Maintain a register of all backflow prevention devices, including the device types, and test results.

A key change in the proposed rules relates to accessing a network with a standpipe. This will only be permitted by Fire and Emergency New Zealand, the water supplier themselves, and their authorised contractors.

Road workers, water carriers, and others who have previously used standpipes to access networks will be required to fill their trucks from designated filling stations.

Changing the rules won’t solve the problem of backflow alone. Taumata Arowai acknowledges that it will take time and resources for the water sector to adjust, and for water suppliers to gather the backflow risks in drinking water expertise and resources needed. For this reason, the timeframes for complying to the rules will be phased in over several years, providing sufficient time for water suppliers to understand the requirements and to put appropriate backflow measures in place.

Drinking water principal advisor Jim Graham consulted with water suppliers around the country before preparing the rules which he presented at the Water New Zealand Backflow Conference.


The transitional provisions in the Water Services Bill will set out when different supply types need to comply with the new rules.

Taumata Arowai is required to publicly consult on the proposed rules and will be welcoming feedback through a public consultation process as soon as possible after the Water Services Bill is enacted.

These new rules provide a challenge to us in the water sector to lift our game. As the water services regulator, it’s the role of Taumata Arowai to raise awareness of the issue, set standards, and help to build and maintain capability among drinking water suppliers and across the wider industry.


This Story is from the September/October issue of Water