New research on Christchurch’s source water
Christchurch City Council Newsline: 6th May 2025
The Water Services Authority – Taumata Arowai (the Authority) has updated Christchurch City Council on research into the city’s water source.
A new study by Environmental Science and Research (ESR) is investigating whether viruses that impact human health – such as norovirus – are present in groundwater taken from deep bores across the region. The research was commissioned by the Authority and is being undertaken in collaboration with the Council and Environment Canterbury.
Watch the Council information session on Christchurch's water (YouTube).
The research is timely as the Authority will be reviewing New Zealand’s Drinking Water Quality Assurance Rules for large supplies later this year.
“This won’t come as a surprise to Christchurch residents who already know we have some of the highest quality water in the world, but this research will potentially save us more than half a billion dollars,” says Deputy Mayor Pauline Cotter.
“This is promising research that builds on international science, and we’re proud to be working collaboratively with the Authority and our regional partners to support this important work.”
Given the complexities of the supply and the amount of investment required to upgrade our network, it will still be a challenge to be successful in a residual disinfection exemption. The Authority has advised that chlorination of Christchurch’s water will still be required to ensure we meet government rules around how water is distributed across our network.
The study uses a new testing method involving a harmless virus found in the human gut – as an indicator of human viral contamination in the same way E. coli is used to signal bacterial presence.
With around 90 samples taken from Christchurch, Selwyn and Waimakariri districts, no evidence of human viral contamination has been detected in any of the deep bore samples tested so far.
A final report is expected by July and any future rule changes would not take effect before 2027.