Concerns mount over the state of Kaipara's drinking water. Photo / NZME
Concerns over Kaipara’s drinking water have intensified after revelations of non-compliance with bacterial and protozoal standards.
The Dargaville Ratepayers and Residents’ Association (DRRA) said the findings in Kaipara District Council’s annual performance report for 2023/2024 raise serious questions about water safety, transparency, and regulatory oversight.
The report showed the council failed to meet national water standards for both bacteria and protozoa across most of its five drinking water treatment plants.
Dargaville, Maungatūroto, Ruawai, and Glinks Gully were only partially compliant with bacterial rules. Mangawhai achieved full compliance.
Protozoal compliance was not achieved in Dargaville and Maungatūroto - the two plants required to report on it.
The council said the non-compliances – particularly around protozoal testing – were mainly because of electronic reporting failures, including power outages and equipment faults that temporarily disrupted monitoring.
The issues were resolved quickly and did not affect water quality, the council said.
Bacterial non-compliance was linked to equipment and servicing delays, plus issues in Dargaville and Maungatūroto with chlorine levels, pH, sampling gaps, and turbidity.
However, UV disinfection remained operational throughout and any water not meeting standards was diverted or dumped.
Wastewater engineering consultant and DRRA member Jo Floyd said unacceptable protozoal levels could raise the risk of waterborne pathogens such as Giardia and Cryptosporidium.
She questioned whether manual testing could have been undertaken during power outages and equipment failures.
The report also included losses from reticulated water, excluding at Ruawai and Glinks Gully, were also in the performance report and at 37% was well above the 27% target.
Floyd said the water loss rate could indicate inefficiencies in the district’s water infrastructure, often because of leaks, ageing pipes, or poor maintenance.
She said this would waste treated water and increases costs for ratepayers.
The DRRA questioned whether KDC had fulfilled its legal obligations under the Water Services Act 2021 to notify Taumata Arowai when water is or may be unsafe, or when there is a risk to sufficiency of supply - such as in Dargaville during May this year - or when water fails to comply with Drinking Water Quality Assurance Rules (2022).
Taumata Arowai, the authority established in 2021 to act at the national water standards watchdog, said it was not concerned about the incidents, which weren’t required to be reported under its criteria.
Taumata Arowai acting head of operations Melinda Sando said it had, however, received appropriate notifications about other incidents, including when Dargaville’s water supply almost ran dry in May this year.
The DRRA challenge KDC’s claim that the drinking water was compliant throughout that time.
Sando said non-compliance didn’t always mean unsafe water was supplied. Suppliers had to assess that risk and decide whether notification was necessary.
DRRA chairwoman Rose Dixon said the performance report findings added to the group’s separate and ongoing concerns about another local water quality issue - elevated aluminium (Al) levels in the Northern Wairoa River.
Kaipara District Council holds a resource consent for the Dargaville Wastewater Treatment Plant that permits a rolling average of 3200cu m/day to be discharged into the river, as well as peaks up to 10,000cu m/day in wet weather.
The DRRA said independent water samples it commissioned in July 2024, supported its theory that the elevated aluminium levels were directly due to that discharge.
It challenges a subsequent report by the Northland Regional Council (NRC) which concluded the high levels were primarily due to surface runoff.
This was despite its test results showing the amount of aluminium in the river adjacent to the wastewater plant at 9.1g/cu m – 165 times more than the national standard for fresh and marine water of 0.055mg/L.
The NRC report found: “These conditions, which mobilise aluminium from soils and eroded riverbanks, were observed across multiple sites and supported by long-term State of the Environment monitoring data.
“Because pH levels (another water quality indicator) remained within the typical range for Northland rivers, the aluminium was less likely to be toxic.”
Kaipara District Council said sludge from the aluminium (Polyaluminium Chloride) used in its drinking water treatment is flushed into the wastewater system, eventually reaching the Dargaville plant but at a level well below consented limits (0.038mg/L). It then went through various filtration processes.
Floyd said the possibility that the aluminium pollution in the river came from the wastewater plant should not be so easily dismissed.
The pH (acidity/alkalinity) of the ponds also needed to be tested as it could cause particulate aluminium, which would normally sink to the bottom of the ponds, to dissolve and go through the system into the river.
Dixon wrote to NRC about her concerns over the report, but the letter went unanswered.
She escalated the concerns to the Ombudsman. However, he referred the matter back to NRC, which Dixon believed undermined public confidence in the regulatory process.
Sarah Curtis is a news reporter for the Northern Advocate, focusing on a wide range of issues. She has nearly 20 years’ experience in journalism, most of which she spent court reporting in Gisborne and on the East Coast.