Contractors are expected to start on a multimillion-dollar project to replace 13km of water pipes in Northeast Valley and Opoho from next year.
The pipes are up to 100 years old.
Work to replace what the Dunedin City Council said yesterday were ''old and poorly performing water, wastewater and stormwater pipes'' is expected to start in February and not finish until early 2020.
The council said the work would improve the area's water pressure, which it said was well below the firefighting standard.
However, some residents will have to wait until after that to get increased pressure.
Council capital delivery team leader Dominika Biziak-Kochan said the main aim of the work was to improve flows for firefighting, but residents would also benefit from fewer burst pipes and unplanned shutdowns.
Northeast Valley had been identified as one of three areas in the city where stormwater and groundwater entered the wastewater network, particularly in heavy rain.
''When we replace the wastewater pipes, we should see fewer of the overflows that cause manholes to pop up in heavy rain.
''The overflows to Lindsay Creek in heavy rain should also reduce, but the problem won't be completely solved at this stage,'' Mrs Biziak-Kochan said.
There would be water shutdowns and streets would have to be closed, but Mrs Biziak-Kochan said the council would work with contractors to minimise disruption to residents.
Traffic management would be implemented in streets where work was being done.
A council information sheet for the work said water mains were mostly cast iron, which corroded over time and caused discolouration and lower pressure.
''This work won't completely resolve all issues with the area's water supply,'' it said.
Some residents would still have fairly low water pressure, and discolouration might occasionally occur.
Council acting planning and delivery manager Jared Oliver said work after the end of the project in 2020 would change pressure zones in the area to deal with that.
Areas at the bottom of the valley had higher pressure, and up towards Opoho lower pressure, and that work would deal with the problem.
Mr Oliver said replacement of other cast iron pipes in the area would deal with any discolouration in future.
Although the cost of the work would not be known until contracts had been let, it would be in the millions, he said.
