Nitrate levels in Ashburton drinking water have been labelled "outrageous" by Greenpeace campaigner Christine Rose, but Environment Canterbury says the portrayal of the results is "misleading".
Early test results found "extremely concerning" contamination in 77% of samples from the area.
Greenpeace offered free drop in water testing in the area over the weekend and tested more than 100 samples.
A similar testing event was carried out in October 2021 which showed that the area’s drinking water was “loaded with nitrate contamination”.
Speaking to Breakfast this morning, Christine Rose says safe drinking water is a basic human right and people should be concerned.
"It's outrageous that there has been inadequate action on this problem given that we know it's real, we have evidence from scientists that indicts that 100 people a year may be getting bowl cancer from nitrates in drinking water and 40 people a year may be dying from it."
"The lack of action from the Government when the cause is known, too many cows and too much synthetic nitrogen fertiliser, it's really tragic."
The New Zealand limit for nitrate in drinking water is 11.3mg per litre, which is in line with the World Health Organization, but 11% of the samples Greenpeace tested exceeded that limit.
"People are being exposed to unnecessarily high, dangerous, and unacceptable levels of nitrate contamination above the New Zealand standard.
"But it's important to realise that that standard in New Zealand was set in the 1950s and public health professors say that it's hopelessly out of date and emerging evidence from huge studies around the world shows that even over 1mg per litre of nitrate in drinking water can be hazardous and lead to elevated risk of bowl cancer and things like preterm birth."
Asked what needs to happen, Rose said the Government needs to phase out synthetic nitrogen fertiliser and reduce the dairy herd.
"That is fundamentally what the Government needs to do because here and here and around the world dairy cattle is the main source of nitrate in drinking water."
She says the number of dairy cows has doubled in New Zealand between 1990 and 2019 and the amount of synthetic nitrogen fertiliser being poured on land has gone up 700%.
"It's too much, it's outrageous, the Government needs to act now to keep people's drinking water safe."
Greenpeace test results 'misleading'
Environment Canterbury's director of science Dr Tim Davie says Greenpeace's results are "misleading".
Davie told 1News: "We absolutely recognise the problem but would like to clarify that Greenpeace is being misleading in the way it has presented the results of its samples taken on Saturday by using statistics based on a single Danish study rather than New Zealand’s Drinking Water Standards, set by the Ministry of Health and Taumata Arowai."
He said the New Zealand drinking water standards set a maximum acceptable value of 50 milligrams per litre (mg/l) for nitrate, which is equivalent to 11.3 mg/l nitrate-nitrogen.
"This is based on the World Health Organization standard. A 2018 review of the science behind the WHO standard, which included the Danish study, concluded there was not enough evidence to change those limits."
Davie also said it's important people understand the Greenpeace samples were taken mostly from private wells on rural properties and not the main Ashburton town drinking water supply.
"We welcome the raising of awareness of reducing nitrates as an important issue for environmental and human health and continue to work closely with other agencies and landowners on this issue."
Colin Hurst of Federated Farmers said farmers are reducing their impact on the water, but it will take time to fix.
"It's something farmers have been well aware of, the increased nitrate in waterways. We're on the journey with this, we've known about this for about 10 to 15-odd years, and we're working on it really hard, there's reductions going on, for example fertiliser use is down 12%."
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