Greenpeace has raised fresh concerns about two urban water supplies in Canterbury after its testing showed high nitrate levels.
In both cases the testing was in line with the local council testing.
Independent testing by Greenpeace of the Ashburton town water supply revealed a sample had reached nitrate contamination levels of 9.65mg/L.
Appelbe did not clarify where the high sample came from in Ashburton and there was no breakdown of the other results.
However, Greenpeace said it “was not claiming that the sample represented the entirety of the Ashburton region”.
“It is a water sample from the Ashburton municipal supply, and it has tested at 9.65mg/L of nitrate. That is, in and of itself, deeply concerning.”
Appelbe said there is a growing body of science showing an increased health risk associated with levels of nitrate in drinking water lower than 11.3 mg/L maximum level.
Ashburton District Council’s regular testing shows water from the Tinwald treatment plant consistently tests around 9.5, while the other three Ashburton plants (Domain, Bridge St, and Argyle Park) are around 2.
Infrastructure group manager Neil McCann said the council regularly monitors the nitrate levels in the Tinwald bore.
“If the MAV was exceeded, immediate action would be taken, including isolation of the Tinwald bore and public/Taumata Arowai notification.
“Council has talked about drilling a new bore for Tinwald or making the existing one deeper, but no decision has been made yet and further investigations are required.”
The council will construct a new water main across the new Ashburton River bridge, providing another layer of redundancy for the supply of water to Tinwald, he said.
Tinwald’s nitrate levels “are relatively high” but they’re still below the Drinking Water Standards’ limits, so the water is safe to drink, McCann said.
Greenpeace also held a water testing event in Darfield this month.
It tested around 100 samples in Darfield, and the town supply averaged 5.45 mg/L, with all 31 unfiltered samples from the town supply reading at levels above 5 mg/L.
Selwyn District Council testing shows the Darfield supply fluctuates between 4.54 and 5.98 this year.
The only source that regularly records over 5.65 (half -MAV) is a Rolleston water treatment site that is listed as a backup site, and is mixed with other sources if used.
“Through the long-term plan, the council has committed to investigating the development of a new low-nitrate water source as part of our ongoing commitment to providing high-quality, reliable water services.
“As Selwyn Water Limited prepares to take on operational responsibility, we fully support the council’s commitment to transparency and ongoing investment in high-quality, low-nitrate water sources.”
Based on the testing, Appelbe was demanding that councils “must make the community aware of the risk and provide an alternative safe source of water”.
Ashburton and Selwyn councils say they already do.
As water suppliers regulated by Taumata Arowa, they are required to collect nitrate samples monthly from all council public drinking water supplies and the results are published online.
Greenpeace also found that 9 private bores in the region were testing well above the legal limit for nitrate in drinking water, with the highest reading at 15.1 mg/L.
Private bore maintenance and monitoring is the responsibility of the bore owner, but Appelbe was critical of Environment Canterbury’s management of freshwater in the region.
"ECan must immediately stop dairy expansions and phase out the use of synthetic nitrogen fertiliser to protect rural communities’ drinking water here in Canterbury.
“They declared a nitrate emergency in September, and it’s time they put their money where their mouth is.”
Following its nitrate emergency declaration, ECan is holding three council briefings relating to nitrate this week and next week, with more anticipated in early 2026.
In a statement, an ECan spokesperson said that since the National Policy Statement for Freshwater Management was repealed any tougher rules on dairy expansion or fertiliser use would need a public plan change, which is currently blocked by the Government’s plan freeze.
Ecan’s existing plan still controls farming impacts, including effluent discharges, and consent planners must assess proposals against national and regional limits.
“If a proposed dairy conversion results in the same or lower nutrient losses than the current land use, consent can be granted.”
The council water quality data can be found here:
LDR is local body journalism co-funded by RNZ and NZ On Air.
