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Chlorination knife-edge

Martinborough’s boil water notice remains in place. PHOTO/FILE

E.coli contamination cause still not established
Race on to protect vineyards as temporary treatment agreed

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A knife-edge balancing act will have Martinborough’s water chlorinated from May 13 – and frantic work in the meantime to find a way to stop the chemical devastating wine-making operations.

At this stage a temporary measure, chlorination will last at least six months.

An emergency meeting of South Wairarapa District Council on Wednesday heard that winemakers only raised alarms about the use of chlorine at 4.30pm on Easter Thursday, shortly after plans for the meeting were announced.

Acting council chief executive Jennie Mitchell said Regional Public Health authorities wanted chlorination to start urgently – “tomorrow”.

Helen Masters

But Helen Masters, head winemaker at Ata Rangi vineyard, told councillors even tiny traces of chlorine in water would make wine unsaleable.

“Chlorine must not enter winery water systems – this is a fact the world over,” she said.

Chlorine at even parts per billion can react with micro-organisms in and around wineries to form a chemical known as TCA which was “almost impossible to remove”.

“It is detectable by the human nose at lower than current testable levels and renders the wine unsaleable,” Masters said.

“Especially vulnerable are the extremely expensive oak barrels which are an essential part of making world-class wine.”

Despite widespread publicity about ongoing issues with Martinborough water, including chlorination of part of the system during the town’s first E.coli incident earlier this year, Masters said winemakers did not consider the chlorination issue.

“We all felt the problem had been rectified.”

Mitchell said the council was under extreme pressure to get the boil notice lifted.

“We’re on a bit of a knife edge. We have Regional Public Health breathing down our neck saying ‘you must chlorinate’, but we now also have the needs of the wine industry to consider.”

The question on Wednesday became how long public health officials would tolerate the council delaying chlorination before imposing it themselves.

Proceedings were adjourned to allow Mitchell to discuss timeframes with RPH.

She returned with a two-week window – and admitted she was pushing the council’s luck by suggesting Monday, May 13, for the start date, taking into account the shortened work week due to Anzac Day.


Before the start date, the council will work with 39 winemakers using the town water supply, as well as several breweries, and olive operations, to determine what is required to address the chlorine issue.

Carbon filters are the likely solution.

“We’ll work through this and come up with a solution that will take the town forward,” Masters said.

“We don’t have to make this a big drama.”

That horse may have bolted, with council officers working throughout Easter to come up with a solution to what was a surprise.

It says the possibility of chlorination had been raised in the past without any adverse reaction from wineries.

Before it starts, the entire Martinborough network will be flushed, which should reduce the amount of manganese in pipes.

Manganese occurs naturally in Martinborough water and reacts with chlorine causing discolouration of water.

The council is also able to draw supplies from a bore with low manganese content.

While the decision is for temporary chlorination, it is unlikely Regional Public Health would allow it to be stopped without the cause of the latest E.coli contamination incident having been identified.

That looks virtually impossible.

Bores and the water treatment plant have been ruled out as the source, with the focus now on the 1100 connections to it, with backflow from one or more of these a possibility.

Councillors were unanimous in the need to take action fast.

Councillor Brian Jephson said all parties needed to be involved.

“The pressure’s on. We need to get this over and done with . . . We [also] need to put the pressure on them [winemakers]. We are trying to do the best for all but public health is paramount.”

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