Council plans to become class 1 water supplier, bypass treatment rules
Wednesday, 11 October 2023
Christchurch’s water supply technically leaves 170,000 people at risk of exposure to protozoa, but the city council’s head of Three Waters says residents shouldn’t worry and it has a plan.
The latest update comes as mayor Phil Mauger says a representative from Taumata Arowai, the national water regulator, has agreed to attend an upcoming Christchurch City Council meeting.
In a press release, Brent Smith, the council’s head of Three Waters, said instead of putting protozoa treatment barriers into its water supply (as requested by Taumatua Arowai, following the recent cryptosporidium outbreak in Queenstown), the council planned to become a class 1 supplier.
Reaching the threshold of class 1 status was not achievable for all of the council’s water sources, but could be for most, he said.
Most of Christchurch’s water comes from aquifers (an underground water source). If the city drew that water from a depth of 30m or more, it could meet the water regulator’s class 1 requirements and would not require a UV treatment barrier.
The upgrade programme, which includes “intensive testing”, was 42% complete.
Smith said the first batch of monitoring would be complete in April next year, and the last groups by December 2025, the same month as Taumata Arowai’s deadline.
Despite how much work was required, the current risk of protozoa contamination in most of the water supply was already very low, based on extensive studies, he said.
Of the council’s 148 registered water sources, only 11 are ineligible for class 1 status. In these cases, the wells would be deepened, removed, or replaced.
Tanner pump station and the Wainui treatment plant (which Smith said was not included in the suite of Christchurch projects) would receive UV treatment barriers.
The Christchurch City Council was one of 27 councils that Taumatua Arowai recently wrote to, telling them they needed to lock in plans to fix their drinking water supply by June 2024, and have it done by December 2025.
Waimakariri (including Rangiora and Pegasus), Hurunui, Buller, Queenstown, Wānaka, Greymouth, Gore, Cromwell, and Motueka are also on notice. In the North Island, areas in Taupō, Whakātane, Thames Coromandel and Auckland were also written to.
As of October 9, the Queenstown outbreak included 65 confirmed and 18 probable cases of cryptosporidium, which causes symptoms including nausea, vomiting and diarrhoea. Another 26 cases are under investigation.
In addition to a lack of protozoa barriers, the Christchurch City Council had clashed with Taumatua Arowai over whether it needed to add chlorine into its water supply.
The water regulator told the council it planned to decline its application for a chlorine exemption earlier in the year, highlighting a lack of a primary treatment barriers, lack of site and system specific risk management plans, and lack of evidence or investigation into source water risks and quality.
It sparked outrage from Christchurch residents and representatives, particularly as it followed almost $200 million worth of improvements to water infrastructure since 2018 precisely so the council could avoid adding decontaminates.
The council invited Taumatua Arowai to send a representative to one of its meetings, so it could put its case forward in the public arena.
Mauger told The Press that invitation had been accepted, but no firm date had been set.