Take ‘emotion’ out of water row

Wednesday July 10, 2019 Written by Published in Local

Chlorination is the “only way” to keep Rarotonga’s water pipes safe and clean, say two experts.

 After weeks of mounting opposition to chlorine in the new drinking water, proponents of the disinfection technique have finally spoken up. Rarotonga plumber Ian Ibbetson says chlorine is the only way to clean the “gunk” from the island’s pipes; financial secretary Garth Henderson says chlorine is “both efficient and effective”.

The men spoke out after new lobby group Te Vai Ora Maori revealed government had already tendered for a chlorine supplier, raising fears the  “public consultation” meetings were a sham.

Ibbetson, owner of PTS Plumbing, said chlorine would “keep the pipes sanitised”.

“People over-react. With the concentration of it, once the chlorine is in the tanks it disappears, like Janola. There’s so little of it, it dissipates.

“Chlorination costs less, it’s directed into the pipes; the lagoon and plantations will be fine, there’s no direct contact with the rivers etc. UV filters work, however they use a lot of electricity and it doesn’t chlorinate the pipes, when you change the UV bulb there is still bacteria living on the other side.

“People get too emotional, if we have to chlorinate, so be it,” said Ibbetson.

International experts are in agreement that drinking water should always be disinfected and the source of the water be protected from agriculture such as pig farming. Waterborne illnesses kill 4000 children a year, the United Nations says – and chlorine is the most efficient and affordable antidote.

Financial secretary Garth Henderson, chairman of Te Mato Vai and Mei Te Vai Ki Te Vai, said: “Chlorinating drinking water is effective at killing harmful organisms in the water such as bacteria and viruses.

“To achieve World Health Organisation standards for safe drinking water, the water pipes also need to be kept free from contamination. “

He argued that chlorine was “the only way to achieve this”. “If another disinfection method was used to treat the water, chlorine would still be added to keep the pipe network safe.”

“Chlorine is the world’s most commonly used water disinfection method and it is a safe and proven method, with countries such as Fiji, Tahiti, Australia and New Zealand using chemical disinfection,” said Henderson.

Introducing chlorine into the water system would take place immediately downstream of the gravity filters at each intake. “It is only after the AVG filters that the water quality is appropriate for disinfection to take place effectively; the storage tanks will hold disinfected water.” 

2 comments

  • Comment Link Andy Kirkwood Friday, 19 July 2019 04:29 posted by Andy Kirkwood

    *The storage tanks should definitely not hold chlorine disinfected water.*

    Henderson is correct that chlorine should only be added after sediment has been removed (requires less chlorine), however stored water will still contain a large amount of fine particulates - organic and non-organic matter (OM-NOM).

    Extended contact times between OM-NOM + residual chlorine in the storage tanks will result in the production of the toxic Trihalomethane (THM) by-products that have been extensively regulated against in the US and other countries. Our stored supply will be the more toxic.

    There is also the question of the suitability of the metal (stainless steel?) tanks use for storing chlorinated water. I am unsure as to the steel grade used in the tank construction, but see Safety Data Sheet note below.

    From Radox Safety Data Sheet (Calcium Hypochlorite)
    ----------------------
    *Conditions to Avoid*
    Conditions of Instability: Reacts with acids, evolving chlorine, an irritating, corrosive and toxic gas. In the presence of moisture, corrosive to most metals. Dust irritates mucous membranes.
    Corrosivity: Extremely corrosive in presence of aluminum, of zinc. Corrosive in presence of steel, of copper. Slightly corrosive to corrosive in presence of glass, of *stainless steel(304), of stainless steel(316)*.
    ----------------------
    *More research required.*

  • Comment Link Matt McGovern Wednesday, 10 July 2019 20:06 posted by Matt McGovern

    Alas, your local experts are sadly misinformed....please check why major NZ cities are considering taking chlorine out or already have so...perhaps it is a cover up for an inadequate water infrastructure

Leave a comment