Photo: 123RF
The national water regulator has turned down an application for Christchurch's water to be exempt from chlorine.
The Water Services Act 2021 made chlorination mandatory for reticulated water supplies, unless an exception is granted by the regulator, Taumata Arowai.
Phil Mauger Photo: RNZ / Nate McKinnon
Christchurch City Council applied for an exemption in October last year and Mayor Phil Mauger said he was outraged to learn it had not been granted.
The news was bitterly disappointing for the elected members after the council had considered the issue over a number of years, he said.
Staff would begin adding the chemical from today, but it would take weeks before all areas were chlorinated.
Tiny amounts of chlorine are overwhelmingly recommended by health experts globally to kill harmful natural organisms that can grow in water, such as bacteria, viruses and parasites, to make it safe to drink.
Without it, the World Health Organisation says people would be exposed to diseases that can range from unpleasant to fatal and crippling.
In 2016 residents of Havelock North were infected by campylobacter that had entered a bore that was previously thought to be very clean.
Up to 8000 people in the area were infected and about 5000 became ill, with about 45 people hospitalised. The infection is thought to have contributed to the death of up to four people, and others were left with long-term disabilities.
In February 2021, a weeks-long boil notice water was issued for parts of Banks Peninsula after dead animals were found in the Akaroa water supply.
"Disinfection of drinking-water supplies with chlorine is widely regarded as one of the most significant
public health interventions, reducing the incidence of waterborne disease globally," a 2017 WHO report said.
Read the full report:
World Health Organisation: Principles and practices of drinking water chlorination, (4.8MB)
And: "In humans and animals exposed to chlorine in drinking-water, specific adverse treatment-related effects have not been observed," the organisation has advised in multiple reports.
Read one of the reports:
World Health Organisation: Chlorine report, 2003, (202K)
Christchurch had the country's largest supply of untreated drinking water. Most of the supply comes from wells deep underground, but some is from shallow bores.
Mauger said the council would continue to fight the move and advocate for the people of Christchurch.
