19 Jul 2016

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High nitrate levels found in two samples of water taken from a bore in an industrial part of Addington are unlikely to have had any adverse effect on people’s health, Christchurch City Council and the Medical Officer of Health say.

Higher than recommended levels of nitrate were detected in samples of water taken from a shallow water supply bore on Wrights Rd in Addington in November last year and February this year.

The cause of the contamination is unknown but animal effluent is a likely source.

The Wrights Rd bore is the only bore in Christchurch to have shown higher than recommended nitrate levels and that bore is being closed down.

Because the Wrights Rd bore is the only one to have shown a spike in nitrate levels it appears the problem has been caused by ‘point source’ (or isolated) contamination and is unrelated to any other increase of nitrates on the Canterbury Plains.

Canterbury Medical Officer of Health Dr Alistair Humphrey said the two isolated spikes in nitrate levels were unlikely to have caused any adverse health effects.

The area where the bore was located was primarily an industrial area although there were a number of childcare centres within the catchment.

“Only children who are aged under six months are at risk from nitrates. If you have been feeding your child formula using water taken from a tap in that area your child would only be at risk if they were being continually fed the water and the water was continually high in nitrates. That is not the case here,’’ Dr Humphrey said.

The Canterbury District Health Board had not had any reports of any baby being affected.

Christchurch City Council Head of Three Waters and Waste, John Mackie, said the Council had visited each of the seven day care centres in the area today and taken fresh samples of water to test. Those results showed the nitrate levels were well within accepted levels.

The Council had decided to shut down the Wrights Rd bore and would be drawing water for the catchment between Blenheim Rd, the Southern Motorway, Annex Rd and Wrights Rd from alternative sources.

The Wrights Rd bore was a shallow bore that had been on the Council’s list to replace by 2018 with a deeper bore that would tap into the confined aquifers which were less susceptible to contamination.