Whangārei Heads Wastewater Scheme

We began a pilot study in Parua Bay focusing on the area immediately upstream of the storage tank where the majority of connected Parua Bay properties are located. 

The study was completed in May 2025, revealing issues within the public network as well as on some private properties. 

Smoke testing showed remedial work was required at various manholes on public and private land, including sealing and repairing lids, particularly those located in low-lying areas that are susceptible to flooding.  

Evidence of H₂S attack was also found, which is where a build-up of hydrogen sulfide causes corrosion of a manhole’s walls, making them vulnerable to stormwater and groundwater leaking into them. 

Remediation of these issues, which involves sealing all damaged manholes, and using CCTV to check and then repair the pipes feeding into them, was carried out by our stormwater and wastewater maintenance contractor.  

We also engaged with the owners of properties within the pilot study area through surveys and site visits, to explore whether stormwater could be entering gully traps from downpipes, which ultimately feed into the wastewater network. 

While most gully traps on private property were in good condition, there were some that were damaged, incorrectly sealed or set too low, making them susceptible to stormwater inflow.  

Others were located in areas that are prone to flooding and could be overtopped in rainfall events, and some properties also had stormwater being directed into gully traps via downpipes.  

We are following up with these property owners, prioritising issues that will be causing the most inflow in the system.

Find out more about smoke testing:

Smoke testing in our wastewater network 

The Parua Bay system is connected to and therefore impacted by what happens further up the catchment. 

Our monitoring during the Parua Bay pilot study indicated that stormwater was entering the system from the Taurikura Bay and McGregors Bay catchments, so we extended the pilot study to these areas. 

This work follows the same model as the pilot study in Parua Bay, beginning with a questionnaire for residents. 

The questionnaire sought to understand any ponding or flooding related issues that tend to occur during rain events on or around private properties. This helps to highlight any wastewater and stormwater drainage issues, as well as possible fixes. 

Investigations in these areas have been completed, and items of interest are being followed up so that they can be resolved.

The volumes flowing into the wastewater system are being monitored 24/7 via flow meters located at several pump stations in the area and level sensors at the Parua Bay pump station storage tank. 

Where our monitoring shows high levels, we are emptying out the storage tank(s) by sucker truck to ensure it doesn’t lead to an overflow.

To help reduce the odour, we have modified the storage tank lids, so they don’t need to be fully opened to do this.  

Wastewater systems are designed to take the wastewater that comes from showers, baths, washing machines, toilets and other household or business sources from the property to a wastewater treatment plant, where it is treated before being disposed of.

In Whangārei Heads, wastewater from household connections flows through wastewater pipes and is pumped to the wastewater treatment plant on Kioreora Road via a series of pump stations. 

The pump stations store wastewater for a while and, when they reach a certain level, the pump sends a manageable amount of wastewater to the next pump station along the pipeline. 

This system depends on every pump along the line working properly, and pumping out at the right time to a storage tank that is empty enough to take the new load.

This cycle works well when wastewater is coming into and being pumped out of the system steadily, but not when there are big fluctuations and very large quantities of wastewater mixed with stormwater coming into the tank very suddenly. When that happens, the tank can be overloaded and there can be an overflow.