The Dunedin City Council plans to install two larger pumps in Carlyle Rd and Reid Ave, after the stations failed to handle more than 120mm of rain that fell in Mosgiel during the July 2017 flood.
That led to stormwater entering the wastewater network instead of draining into the Silver Stream.
The new pumps would be able to discharge about three times more stormwater.
Work to replace the Reid Ave pump was scheduled to start late last year, but was pushed back to the end of this year.
The Carlyle Rd pumps were due to be replaced like-for-like this year to improve their reliability, while work was done to upgrade the pumping station.
But the council's 3 Waters group manager Tom Dyer said last week construction would now start in the middle of 2020.
"Our initial design for the Reid Ave pumping station has been completed, peer reviewed, and we have started working through a number of different consent applications with Otago Regional Council and engaging with relevant stakeholders.
"These early and important conversations have flagged some changes to our initial design which will take some time to implement."
The changes included additional erosion armouring on the Silver Stream river banks, changes to how the outlet pipe is constructed, and further work to understand the potential impact on the performance of the Silver Stream flood protection scheme.
"In the meantime, we have established contingencies, such as large mobile diesel powered pumps, to increase the capacity of the Reid Ave pump station during heavy rain events," Mr Dyer said.
"We have also started engaging with the construction market and have shortlisted contractors."
