Sydney Water will start replacing water mains along Industrial Road, Oak Flats later this month in work that may cause disruption to residents and congestion on local roads, Shellharbour MP Anna Watson said.
When under way, work hours will be from 7am to 6pm Monday to Friday and 8am to 1pm on Saturdays if required.
The work involves excavation in the footpath, disconnecting the old main and laying a new one.
Some interruptions to the water supply may be necessary.
It is estimated the work will take up to 12 weeks to complete.
Sydney Water will notify customers of any planned interruption to the water supply.