Moves to show our water supply complies with rules
Christchurch City Council Newsline: 10th October 2023
Christchurch City Council is underway with an extensive testing programme to demonstrate most of the city’s water supply can comply with drinking water rules and standards without a protozoa barrier.
Following the outbreak of cryptosporidium in Queenstown caused by water contaminated with protozoa, Government water regulator Taumata Arowai wrote to the Council outlining its expectation that protozoa treatment barriers are put in place for water supplies that draw from bores with a depth less than 30m.
It set deadlines of 30th June next year for plans to be in place, and 31st December 2025 for barriers to be installed and operating.
However, the Council expects to be able to demonstrate Class 1 status for most of the city’s water supply - which means it will comply without having to install protozoa treatment barriers.
Class 1 status can be achieved when the water source is drawn from deeper than 30m, the well heads meet the requirements to be considered a sanitary bore, and an intensive sampling programme is completed.
“I want to reassure residents that while our water supply currently is non-compliant with the rules. The water is very much safe to drink,” Head of Three Waters Brent Smith says.
“Christchurch city’s water supply is unique due to the deep aquifers we draw from. Based on extensive studies there is evidence to show that the risk of protozoa contamination is very low.
“We’re already in the process of establishing a programme of work to achieve compliance. This includes the current intensive testing programme to meet the Class 1 criteria. This programme is already 42% complete and has so far has achieved good results.
“The first batch of monitoring will be complete at the end of April 2024 and the last groups will be complete in December 2025."
Out of our 148 registered sources, only 11 cannot be considered for Class 1 status as the wells are too shallow or remain in underground chambers.
Projects to address the 11 Christchurch sources that can’t be considered for Class 1 are planned or underway. These include:
- Projects have begun to deepen shallow wells at Montreal and Woolston pump stations.
- Five water sources in the Mairehau, Burwood and Averill pump stations can be permanently taken out of service once rezoning is complete.
- Two sources at Kerrs pump station will be replaced as part of a planned treatment plant replacement programme.
- Two sources at Tanner pump station need a protozoa treatment barrier (UV) installed.
In addition to the 11 Christchurch projects, the Wainui treatment plant also needs a protozoa treatment barrier (UV) installed.
Council staff are working on plans for the Wainui and Tanner upgrades, which need to be prioritised to be complete by the December 2025 deadline.
These will be included in the Long Term Plan 2024-34, which will be considered by the elected Council next year.