The Government inquiry into the Havelock North gastro outbreak is being used to make sure Christchurch does not suffer the same fate.
City council staff have prepared a report for the infrastructure, transport and environment committee outlining the key findings of the first stage of the inquiry, and how they are managed here.
The report looks at five key findings from the inquiry: no lessons learned from previous outbreak, aquifer not confined, high transgression history, poor working relationships and protozoa risk.
In the report, it said the city council had not experienced repeated outbreaks, and it reviewed its operational practices regularly.
It had improved the design of wellheads for new water supply wells to reduce contamination risks. Last year it began remediating the water reservoir roofs.
The report said the programme to fix the unconfined shallow wells in the northwest of the city had been accelerated, costing an extra $250,000, in response to the Havelock North outbreak.
Those wells supplied water to about 80,000 people.
All the shallow wells would be fully decommissioned and replaced by deeper ones by late next year. Up until then, they would be monitored closely, the report said.
As of last month, six out of the 12 shallow wells had been decommissioned.
In terms of excessive transgression events, the city council had no history of that, the report said.
It said in the past five years there were five E.coli detections at water supply wells.
Four out of the five were at the unconfined shallow wells that were now turned off.
The fifth detection was at a confined shallow well in 2014, but was attributed to the flooding of the wellhead chamber during the March floods.
The report said the city council was unlikely to have poor working relationships, as it was revealed in the Havelock North inquiry, as it had established relationships with relevant organisations.
It said protozoa was never found in samples taken from the unconfined, shallow aquifers.
The Havelock North outbreak caused more than 5000 people to become ill with campylobacteriosis, with about 45 hospitalised.
It has been linked to three deaths.
The contamination was found to have entered the town’s drinking water bores.
Stage two of the inquiry is due to be released in December.