Lane closures along a stretch of Winchester Road and Hatch Warren Roundabout will now begin on Monday, September 11 – a week later than originally planned.
South East Water is carrying out two weeks of work to connect new pipes it has laid up to the existing water network.
Highway restrictions have seen the work delayed by a week.
Motorists are being warned of disruption while the £75,000 scheme – part of a larger project to expand the capacity of the underground water network – is completed.
Matthew Cooper, project manager at South East Water, said: “The safety of motorists and our workforce is our top priority when carrying out work, which is why we will need to have this temporary lane closure in operation.
“This lane closure will keep traffic flowing through the area and keep disruption to a minimum.
“We expect this work to take approximately two weeks to complete but our contractor will be working as safely and quickly as possible to complete this work.
“I would like to apologise for the disruption this work will cause but hope motorists and the local community understand the long-term benefits this scheme will deliver.”