Christchurch City Council has released an action plan to address the shortcomings found in an independent report into its Three Waters department.

The author of the report, consultancy KPMG, found the department had dozens more positions than budgeted for and had racked up a $6.5m staffing cost blow out since July 2019.

In response, the council said key staff had developed an action plan to improve its systems and try to prevent similar situations in future.

"The council is currently undertaking a significant level of work to actively address the planned actions based on priority and feasibility," it said in a statement.

The plan addresses 15 findings in the KPMG report with more than 30 planned actions.

Nine were considered high priority, and all were to be in place by the end of September 2024. They included "annual training on minute-taking" for all executive support staff, and training on how to use employment forms correctly for all staff who use them.

Educating staff on the difference between operating expenditure and capital expenditure, formally defining job positions and ensuring the master council job chart was up to date also had high priority status in the action plan.

Most areas of improvement related to new, reviewed or upgraded systems, namely a new Human Resources Information System, the council said.

"Executive and senior leaders at council are committed to improve the council processes and systems to mitigate the risks identified," it said.

Chief executive Dawn Daxendale and chief financial officer Leah Scales had both tendered their resignation this week.

Head of Three Waters Helen Beaumont and general manager of infrastructure, planning and regulatory services Jane Davis had also resigned earlier this year.

Linwood ward councillor Yani Johanson said the public needed reassurance that overspending was being prevented.

Yani Johanson. Photo: Supplied / Christchurch City Council

He said a particularly salient point in the independent report for him was a staffer saying that financial reports in other council departments were also of poor quality.

"The public are rightfully concerned about the ever-increasing costs of council, recognising that we do have a lot of pressures, particularly in Three Waters [area] where we have had central government law reform," he said.

"But it's really important that at a governance level that we do get some reassurance from senior management around the robustness of other departments' information as well."

Johanson said he was heartened by the improvement action plan.

"I think there's a number of really important things that [executive management] had undertaken to address and the key thing is to make sure that we're monitoring that at a governance level, again to make sure that it's implemented," he said.

Mayor Phil Mauger said via a spokesperson that he had no comment to make.