Unacceptably high levels of nitrate contamination in drinking water in Ashburton and the surrounding area are putting residents’ health at risk, says Greenpeace Aotearoa. The organisation returned to the region to offer free drop-in water testing on Saturday, following a similar testing event in October 2021 which showed that the area’s drinking water was “loaded with nitrate contamination”.

Preliminary analysis of the weekend’s testing revealed elevated levels of nitrate contamination in 77% of samples from the Ashburton area. Greenpeace Aotearoa lead campaigner Christine Rose says this is a result of intensive dairying in the region, and is “extremely concerning”.

“Clean, safe drinking water is a basic human right,” says Rose. “No one should have to wonder if the water from their kitchen tap is unsafe to drink – but for many people around Ashburton, and in other rural communities, that is their reality.” 

Worsening nitrate contamination of drinking water is due to a big increase in the use of synthetic nitrogen fertiliser – an increase of 700% nationwide, and a ten-fold increase in the number of dairy cows in Canterbury – over the past 30 years. Synthetic nitrogen fertiliser and cow urine leach into the ground and convert to nitrate, then make their way into aquifers, and from there, into people’s groundwater drinking supplies. According to scientists, rural communities are most at risk of exposure to hazardous levels of nitrate in drinking water.

“There is very high nitrate contamination in rural areas like Ashburton because of the intensity of the dairy industry,” says Rose. “Big dairy, led by Fonterra, maximises profit while polluting people’s drinking water with nitrates, putting communities’ health at risk.”

The maximum acceptable value for nitrate in New Zealand drinking water is 11.3 mg/L, set in the 1950s in response to Blue Baby Syndrome. However, emerging evidence from substantive studies around the world shows potential health risks at much lower levels of nitrate in drinking water.

A Danish study found that at over 1 mg/L of nitrate in drinking water, risks of bowel cancer increase, while a US evaluation found health risks increased with every additional milligram. New Zealand scientists estimate that 100 new cases of bowel cancer and 40 deaths per year are attributable to nitrate in drinking water. A Californian study in 2021 found that when women consumed water that was over 5 mg/L of nitrate during pregnancy, the risk of preterm birth increased by 47%.

“Saturday’s test results reflect what we found when we tested drinking water in Ashburton in 2021 – the majority of samples exceeded 1 mg/L. It’s clear that there’s severe nitrate contamination in the region,” says Rose.

Greenpeace conducted 107 tests in Ashburton this week. Preliminary analysis found 77% of samples above the cancer risk level of 1 mg/L while 38% were above the preterm birth risk level of 5 mg/L. 11% exceeded the current nitrate standard of 11.3 mg/L, including one at 25.7 mg/L. Samples from town supplies in Fairton and Hinds exceeded 5 mg/L, with one showing a maximum recorded value of 8.15 mg/L.

“It’s also concerning that these high results come in autumn, because nitrate levels are usually at their highest in spring,” says Rose.

“The Government must decide whether it will protect drinking water and rivers, or if it will allow big dairy corporations like Fonterra to continue polluting water with nitrate for the sake of maximising profit.

“What we’re seeing here in Ashburton is totally unacceptable,” says Rose. “The Government needs to take urgent action to address nitrate contamination at the source, to protect the health of rural communities.

“That means regulating the intensive dairy industry by phasing out synthetic nitrogen fertiliser, and halving the dairy herd.”

The high levels of nitrate contamination found in Ashburton comes after testing last week in Lumsden and Gore revealed both towns’ public water supplies are over 4 mg/L, nearing the reproductive risk level.

“Locals have seen the increase in intensive dairy farming and the resulting increase in nitrate contamination. Farmers we’ are saying that we cannot continue to farm like this in the future,” says Rose. 

“The Government must support a shift to more ecological farming – plant-based, regenerative, organic agriculture that doesn’t pollute our drinking water or put rural people’s health at risk.”