ANALYSIS: Fluoridating water in Christchurch will be more costly than it would be elsewhere because of the city’s infrastructure design.

Instead of having a few centralised water treatment plants where fluoride can be added, Christchurch has 49 pump stations in the city and the Akaroa water treatment plant where fluoride would need to be added.

New council figures released this week estimated that adding the necessary equipment at all 50 sites would cost $63 million – which is about $1.3 million per pump station.

The council said a realistic timeframe for this work would be six to eight years.

Adding fluoride is proven to help prevent tooth decay and the Canterbury District Health Board has endorsed it.

Water supplies are fluoridated in Auckland, Dunedin, Invercargill, and Hamilton. It is normally fluoridated in the Wellington region too, but it was revealed this month supplies have been unfluoridated for the past four to 10 months.

No part of Christchurch’s water is fluoridated.

A 2020 study by public dental health researchers said the poor oral health of Canterbury children was an “ongoing paediatric health crisis” and that children living in non-fluoridated areas were 20 per cent more likely to have tooth decay.

A report commissioned for the Ministry of Health in 2016 found fluoridation in Canterbury could save between $106m and $318m in dental costs over 20 years.

Historically, it is the city council that has chosen not to fluoridate.

But due to a law change, it has lost the decision-making power to Director-General of Health Dr Ashley Bloomfield, who told the council late last year to start preparing to fluoridate.

Water New Zealand chief executive Gillian Blythe said the number of pump stations in Christchurch meant fluoridation would be “more resource-intensive” than elsewhere.

“In most other places, water is typically pumped to a central treatment station where the fluoride would be added,” she said.

Christchurch City Council three waters boss Helen Beaumont said while larger cities may have more than one treatment plant, none have 50 locations where fluoride would need to dosed.

In Auckland, their water is fluoridated thanks to just six water treatment plants.

Water supplies across Lower Hutt, Porirua, Upper Hutt and Wellington are usually fluoridated from just four plants – though the water has been unfluoridated for the past four to ten months. About 439,000 people live across those four areas.

Christchurch, by comparison, has to fluoridate in 50 locations for about 392,000 constituents.

The extra cost burden on places like Christchurch was highlighted in a 2015 report, written for the Ministry of Health, that analysed engineering costs of fluoridation.

Engineering consultants Beca wrote that Napier had a similar de-centralised system to Christchurch, and that with this type of system implementing fluoride “would cost significantly more”.

Beca estimated at the time that fluoridating in Napier would cost $2.25 million, whereas in Whangarei, which has three treatment plants, it would only cost $725,000. Both areas had roughly the same population.

Beaumont, the Christchurch City Council water boss, said Christchurch’s 49 pump stations were not conventional treatment plants and the addition of fluoride would be more complex.

The system at the pump station is sealed and the station’s control systems were not equipped to monitor and control treatment processes, she said.

“Therefore additional instrumentation and communication equipment would be required to manage the fluoridation process.”

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*Original article online at https://www.stuff.co.nz/national/explained/128236167/christchurch-infrastructure-design-makes-fluoridation-cost-significantly-more

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