Luis Arevalo is about to welcome a grandson into the world but he does not think the child will ever drink from his kitchen tap because of nitrate-tainted water.
His family only drinks bottled water because he is worried about nitrate exposure from the Oxford Rural 1 supply where he lives in Canterbury's Waimakariri district.
Council testing shows nitrate-nitrogen levels between 4.3 to 5.17 milligrams per litre (mg/L) over the past two years, well below the drinking water standard of 11.3 mg/L, but Arevalo is concerned about emerging evidence detailing the potential health risks of nitrate at far lower levels.
"I'm old enough to remember when smoking was okay. I'm old enough to remember when seatbelts weren't needed in cars. When scientists and politicians and organisations and corporations were saying there's nothing to worry about, well, they've been proven wrong," he said.
"If enough scientists are saying we've got a problem here, I dare say we have got a problem."
Arevalo's concern was now even more personal, with the baby on the way.
"Our grandson will probably never drink the water out of the tap," he said.
"We know that what's being dumped in now won't come through for another 20 or 30 years, so we are going to have an increase."
He said the group aims to raise awareness about nitrate levels and the potential risks to people's health.
"Without the right information people aren't going to stand up. What we are trying to do is get as much information as possible out to the public. Governments will not change until their voting base says 'this is not ok'.
"They will be getting away with this for as long as they can."
'Huge number of bores' in breach or close to breaching drinking water standards
Since 1990, Canterbury's dairy herd has increased by about 1000 per cent, to well over a million cows.
Between 2002 and 2019, nitrogen fertiliser use in Canterbury increased 326 percent, while the area being irrigated increased by 99 percent over the same period.
An Earth Sciences New Zealand-led study published in November confirmed that Canterbury has the highest percentage of elevated groundwater nitrates in the country, following testing of 3800 rural drinking water samples from private wells between 2022 and 2024.
Researchers identified nitrate-rich cow urine as a primary cause of contaminated groundwater.
The Canterbury Regional Council's (ECan) latest annual groundwater survey shows nitrate increasing in 62 percent of the 300 test wells.
More than 10 percent of wells tested had nitrates above the drinking water limit, including 18 of the 36 wells in the Ashburton zone.
In September, regional councillors voted nine to seven in favour of declaring a nitrate emergency, although some branded the move a political stunt, virtue signalling and an attack on Canterbury farmers.
University of Canterbury public health associate professor Dr Tim Chambers supports the move.
"There are a huge number of bores now that are either breaching or near breaching the drinking water standard."
The maximum acceptable value (MAV) of nitrate-nitrogen in drinking water was set in the late 1950s by the World Health Organisation (WHO) to guard against blue baby syndrome, a rare but potentially fatal condition caused by nitrates starving the body of oxygen.
New Zealand's drinking water standards set out the maximum amount of nitrate acceptable in drinking water, generally based on WHO guidelines.
A 2021 study co-authored by Chambers found up to 100 cases of bowel cancer and 40 deaths might be caused by nitrate-contaminated drinking water each year, with about 800,000 New Zealanders exposed to potentially hazardous levels.
Bowel cancer is the second highest cause of cancer death in New Zealand, with particularly high rates in South Canterbury.
A link to bowel cancer is in dispute, with Bowel Cancer New Zealand saying current evidence suggests nitrates in drinking water are highly unlikely to increase the risk in Aotearoa, while the Cancer Society notes nitrates can react with other substances when metabolised to form compounds widely shown to be carcinogenic.
Chambers argues the drinking water limit is too high and potentially puts people at risk of pre-term birth and bowel cancer.
"There is a lot of emerging evidence suggesting that level should be lower," he said.
"There are international studies that are linking nitrate with pre-term birth risk and also with bowel cancer. The levels at which we are seeing that increased risk in those studies is much lower than the current MAV, but exactly where it should be set based on that evidence is not clear yet because it hasn't gone through the regulatory assessment."
Most New Zealanders drank from supplies with nitrate at less than 1 mg/L of water but hundreds of thousands of people on private and public rural supplies were being exposed to levels of concern, Chambers said.
On 5 December, the Waimate District Council reported the Lower Waihao and Waikakahi East rural water scheme had reached nitrate levels of 8.8 mg/L, where supplies were off limits for extended periods in 2022 and 2024 because of breaches of drinking water standards.
Chambers said intensive dairy farming in areas with shallow groundwater had resulted in rapid changes to nitrate levels.
"We've had that situation in Waimate where a local drinking water supply went from under one milligram per litre to breaching the drinking water standard in as short a time as six or seven years," he said.
"We need to do better with our environmental management. We need to do better with our source water protection - this lands on the councils. If there is a problem we need to try to find alternate water supplies or apply appropriate treatment methods at the plant before it hits the tap."
'People can't smell it, they can't taste it'
While public drinking water was tested by local councils and the results published online, people on private supplies must do their own testing.
At a Greenpeace-run testing day in Darfield in November, more than 100 people turned up to get their samples checked for free.
Results showed the town supply was about half the acceptable limit but nine private bores were above the standard.
"The problem is people can't smell it, they can't taste it, so they don't even know they're drinking it," the man said.
The College of Midwives advised pregnant women to consider alternative sources, such as bottled water, if nitrates exceeded 5 mg/L - which was less than half of the MAV.
Midwifery advisor Claire MacDonald said a "precautionary approach" made sense.
"When we're thinking about something as fundamental as drinking water we need to take a long-term vision and we need to recognise that what we do now will impact on generations to come," she said.
"The babies that we as midwives welcome into the world, they're going to live well beyond our lifetimes and into the 22nd century and then their grandchildren will live further on, so this is not just about the now. This is about the future."
New council chair Deon Swiggs voted against declaring a nitrate emergency but said he now saw it as a chance to raise awareness about drinking water contamination.
"Once we all have more of an understanding about what it is we can work with the industry to start addressing some of the problems where there are hotspots and where there are issues," he said.
"No one is saying there aren't issues. The last thing we want is people to not believe there's an issue when there potentially is an issue. Get everybody on the same page so we can start addressing it because the industry's the one that's going to need to start addressing some of these challenges."
'People are losing faith in regional councils'
Some political leaders were explicitly against the emergency declaration, including new Selwyn mayor Lydia Gliddon who believed it overstated the district's situation and did not reflect the progress already made.
"Nitrate levels in Canterbury are a long-term legacy issue, largely driven by land-use practices of 20-30 years ago. In Selwyn, farming systems have already changed significantly. Fertiliser use is down, irrigation is more efficient, nutrient limits are tighter and farm environment plans are mandatory," she said.
"What our community needs is accurate information, long-term planning and steady, science-based work, not heightened rhetoric."
Cabinet minister Chris Bishop told RNZ the declaration was "precisely why people are losing faith in regional councils".
"It's political grandstanding and empty symbolism that does nothing to improve the environment and pits rural against urban and town v country," he said.
"The declaration does nothing to improve water quality and undermines decades of collaborative work by farmers, iwi, councils and communities and fuels division and panic rather than solutions. Farmers are reducing synthetic nitrogen fertiliser use and 84 percent of dairy farms now operate under a farm environment plan (compared to 32 percent in 2021)."
Health Minister Simeon Brown said the MAV for nitrates in New Zealand drinking water was consistent with international guidelines, including the WHO, European Union and Australia.
"Drinking water suppliers are responsible for providing safe and sufficient water to the communities they serve. That means taking action to identify hazards, including emerging hazards that relate to their supply and how any risks associated with these hazards will be managed," he said.
Water regulator Taumata Arowai, the Ministry of Health and the Ministry for the Environment also pointed to New Zealand's nitrate MAV as being in line with international guidelines.
In December, Denmark was investigating lowering its legal limit by 88 percent, which is equivalent to a nitrate-nitrogen MAV of 1.36mg/L in New Zealand, because of concerns about bowel cancer risks and nitrates in drinking water.
