Nitrate level request could affect many water supplies

The nitrate pollution limits environmental groups want for New Zealand waterways would also catch out the drinking water for nearly 400,000 people on a registered drinking water supply, a University of Otago researcher says.

University of Otago, Wellington, senior research fellow Tim Chambers said 390,000 people, or about 8% of New Zealanders, were on registered drinking water supplies that would not meet the limit promoted by Greenpeace, Forest & Bird, the Environmental Defence Society and Choose Clean Water last week.

Those groups, and subsequently Fish & Game, have called for the Government to lower the level for nitrate water contamination from 11.3mg per litre to under 1mg per litre.

Nitrates in drinking water have been linked to dairying intensification, and to an increased risk of bowel cancer.

And while New Zealand’s current maximum allowable value of 11.3mg per litre is in line with World Health Organisation advice, it is in place largely to prevent infants from getting a disease that suffocates them from the inside out, called blue baby syndrome.

Dr Chambers said the Government’s water reform proposals — and some of the up to $185billion infrastructure spending needed to provide safe water services — could be used to address registered water supplies that did not meet the 1mg-per-litre proposal.

"If they are going to do this amalgamation with the Three Waters review ... there’ s probably a good opportunity there with the capital available to find alternate water sources for those towns or those supplies that are over 1mg per litre," he said.

A further 250,000 people were on unregistered supplies that were also over 1mg per litre, he said.

Treating drinking water for nitrates was at present both rare and expensive, he said.

Meanwhile, at the weekend, Greenpeace and the Federation of Freshwater Anglers held drop-in water testing in Ashburton on Saturday and Temuka yesterday.

On Saturday they tested 101 samples provided by Ashburton bore owners.

Preliminary analysis showed 61% of those had over 5mg per litre of nitrate contamination.

Ten samples were over the current health limit of 11.3mg per litre, a statement from Greenpeace said.

hamish.maclean@odt.co.nz

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