More than 5 percent of rural drinking water samples in New Zealand exceeded national nitrate limits, with nearly one-third surpassing half the allowable level, revealing widespread contamination risks, new research shows.
The analysis of over 2,400 samples collected between 2022 and 2024 showed the highest contamination levels in New Zealand's Canterbury, Waikato, and Southland, regions known for intensive farming, according to a statement released Tuesday by Earth Science New Zealand (formerly GNS Science).
Unlike public water supplies, rural groundwater bores serving fewer than 25 people are not regulated, leaving many communities at risk of consuming unsafe nitrate levels linked to serious health issues such as cancer and preterm births, it said.
"People from across the country have helped to build a national picture of nitrate contamination hot spots and received vital information about the nitrate levels of their own drinking water supply," said Karyne Rogers, the study's lead author from GNS Science.
Study co-author, Associate Professor Tim Chambers from the University of Canterbury, emphasized that Canterbury faces the largest nitrate issues in New Zealand, attributing high nitrate levels mainly to animal effluent from intensive farming.
Chambers noted the elevated health risks for rural residents, especially infants, and called for a precautionary approach amid ongoing regulatory reviews.