Hope of chlorine-free water for Christchurch residents by end of year

Friday, 5 June 2020

Almost 120 well heads have been raised above ground since June 2018 under major efforts to future-proof Christchurch's drinking water network. (First published 2018)

Residents in Christchurch could have pure, chlorine-free drinking water by the end of the year if the Government approves a new plan to prove supplies are safe.

The disinfectant was brought in two years ago after it emerged wells across the city did not meet safety guidelines tightened in the wake of the 2016 Havelock North contamination that left 5000 people ill and four dead.

A new safety plan submitted to the Ministry of Health last year was rejected in January as being inadequate to protect supplies from potential contamination.

It has since been revised and the city council will resubmit it for consideration later this month.

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Christchurch water boss Helen Beaumont believes residents could have chlorine-free supplies by the end of the year.

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If approved, the plan would allow a further 80 upgraded wells – 122 in total – to be used without chlorine once reservoirs and suction tanks are repaired.

Council water boss Helen Beaumont said that work is expected to be completed in the next six months, paving the way for residential areas of Christchurch to finally be free of chlorine.

Industrial and commercial parts of the central city could take longer as more work is needed.

“I am reasonably confident that we will get it through in the next round,” Beaumont said of the chances of the revised plan being signed off.

“A lot is dependent on us getting it right, but we’re still not aware of any water supplier who has got a water safety plan signed off under the new framework.

“It’s quite a change to the previous framework and there’s a lot of people struggling to both understand the requirements and then ensure that we have sufficient information at the right level to meet those requirements.

“We are working with the panel (of four drinking water assessors reviewing the plan) to make sure that we clearly understand them and to explain what we are doing to mitigate the risks.”

Millions of dollars have been poured into upgrading Christchurch’s water network over the past two years amid nationwide efforts to revamp the country’s creaking infrastructure.

Despite 122 of the city’s 148 wells being upgraded since 2018, the council has faced a series of hurdles to prove its supplies are safe.

Stricter rules around water safety have been introduced amid major efforts to improve New Zealand's infrastructure.

For chlorine to be removed, wells must be signed off by a well-head security expert and then approved by a drinking water assessor (DWA).

But amid a lower appetite for risk, last June the ministry stripped Canterbury’s DWA of the power to approve wells as being secure enough to stop chlorination.

Wells repaired since then have had to be treated, despite posing the same risk as others signed off before that date and that are now unchlorinated.

This forced the council to miss its goal of last September to be disinfectant-free, as only a third of the 122 wells had been approved.

Regulations announced last year also force councils to chlorinate water as part of a “multi-barrier approach” unless they can satisfy a new regulator – still being set up – that they should be exempt.

The upgraded wells supply 89 per cent of Christchurch’s water, but only 20 per cent of the city currently receives unchlorinated water – about 32,000 households – most dosed at 0.2 parts per million. A further 8000, around 5 per cent, have water made safe with ultra-violet treatment.

Approval of the new water safety plan would mean only one signature is needed to confirm water safety is adequate, allowing the other two thirds of the upgraded wells, including 80 supplying mainly residential areas, to be chlorine-free.

The central city will take longer because of work needed to prevent backflow into the network from commercial and industrial premises.

Options for how that works and who will meet the cost are currently being hammered out by council staff.

While the council expects to submit its water safety plan in the next few weeks, the ministry spent three months scrutinising its last effort before rejecting it. A similar wait is likely this time, meaning Christchurch may not get an answer on its revised strategy until spring.

Following January’s rejection the council drew up 57 changes to address 80 elements that fell short of standards.

Seven, including an assessment of all reservoirs and suction tanks, need significant time and effort, and the council has asked that these can be carried out as improvements after the new plan has been approved.