What chemicals find their way into Aotearoa's drinking water?

A new report on the quality of New Zealand’s groundwater has been described as "‘reassuring" as low levels of pesticides were detected.

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Principle scientist, Murray Close says the report indicated levels of pesticides were 200 time below drinking standards. Source: Breakfast

The report, from Crown research institute ESR, identifies decreasing levels of pesticides in our groundwater although the emergence of everyday chemicals were noted.

ESR Principal scientist, Murray Close told TVNZ 1’s Breakfast levels of pesticides were actually 200 times below the drinking water standard after a suite of 90 pesticides were tested. 

Herbicides were the most frequently detected pesticide group making up 88 per cent of the pesticides detected.

“Most of the pesticides, the more modern ones, are much more selective, so you put on less and also much less persistent so they don’t last long enough to get to the groundwater, which is good,” said Mr Close.

The controversial herbicide, glyphosate was barely detected in groundwater.

“We tested 135 samples, we found one detection in a well, that well was just used for irrigation and it was a one metre diameter well, quite a big well and I guess prone to contamination from surface, so we think that has likely come from containers stored near the well,” he said.

Emerging Organic Contaminants (EOC) – chemicals used in everyday life such as pharmaceuticals, Panadol, ibuprofen, voltaren and BPA were also tested.

BPA or bisphenol A, used to make plastic, was the most common EOC detected.

“The drink bottles and the containers we use, it’s everywhere from that point of view,” says Mr Close.

“Generally, where most of the EOCs come from is our wastewater and so the compounds we use go down the sink, go down the toilet and then they end up in the wastewater and that gets into the environment,” he says.

Mr Close says from the point of view of human health it’s a reassuring report.

“Most of these chemicals, we are using in the milligrams or grams sort of level.”

He said that for a consumer to ingest one gram of Paracetamol through drinking water, they would have to drink the equivalent of 200 Olympic size swimming pools.

“They are very, very low levels,” he says.