Chlorination in the pipeline as councillors decide how to keep drinking water safe

Christchurch’s drinking water could be chlorinated for up to a year if councillors approve treatment in an effort to protect the public from potentially dangerous contamination.
An assessment of the city’s wells has found many are in disrepair and vulnerable to pollution from dirty surface groundwater.
* Christchurch’s water should be temporarily treated after report finds drinking wells ‘may be susceptible to contamination’ * Chlorinating Christchurch’s drinking water could cost $100m – council * Chlorinating water in Christchurch’s northwest is off the table * Health officials want assurance D-rated northwest Christchurch water supply safe * Christchurch’s drinking water contaminated 125 times in four years * Positive E coli tests ‘not surprising’ in Christchurch untreated water supply * Havelock North: a village that looks as ghostly as its residents Mayor Lianne Dalziel was only advised of the situation on January 15 when she returned to work after the Christmas break.
Canterbury medical officer of health Dr Alistair Humphrey has emphasised that water is safe for drinking but is calling for temporary chlorination to provide certainty.
A report outlining the issues and options to make water safe was still being drafted late Wednesday afternoon, giving councillors little time to consider them before making their decision.
It offers two alternatives – to accelerate work to reinstate the secure water supply status and temporarily chlorinate, which the council recommends, or to continue the work without treatment.
"Temporary chlorination would cease as soon as possible, when agreed by the drinking water assessor and the Canterbury medical officer of health.
Vulnerabilities in well heads were uncovered last year when engineers began an urgent programme of assessment triggered by a damning report into the Havelock North incident in 2016, when 5500 people fell ill from drinking contaminated water.
Repairing the compromised wells and treating water at the city’s 56 pumping stations would be completed by December and cost an estimated $1.75 million (including $600,000 to install temporary chlorination and $250,000 for ongoing chlorination).
In 2016, councillors went against staff advice and decided not to chlorinate water in north-west Christchurch while it decommissioned shallow aquifers found to be unsafe.

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