Works which were originally expected to run until September 2 will now continue until Friday September 20.
This has forced the closure of Newlands Road. A spokesman for Glasgow City Council said: "Due to engineering difficulties it has been necessary to close Newlands Road between Langside Drive and Clarkston Road.
"It is estimated that the road will re-open on Wednesday August 28. "Due to Scottish Water operations there are temporary traffic signals in place on Newlands Road, and these signals will be moved east as work progresses to Muirskeith Place.
"It is estimated that the works will be complete by 6pm on Friday September 20."
A diversion will be in place via Merrylee Road.
On Sunday, Montrose Street will be closed from Cathedral Street to Richmond Street from 7am for works.
Motorists have been warned to expect delays.