Barwon Water said that the pipeline is critical in ensuring a reliable water supply to Colac and its surrounding district, and the pipeline has deteriorated to the extent where replacement of some sections is necessary.
Approximately 6.2 km of the 28 km pipeline will be replaced, of which 500 m will involve using Trenchless Technology, including horizontal directional drilling to avoid environmentally sensitive areas and waterways.
Barwon Water said that due to difficult terrain and high rainfall in the Otways, work could only be carried out during the summer months.
The pipeline, which connects the West Gellibrand and Olangolah reservoirs to Colac, was originally constructed in 1910.
The project is being delivered by the Barwon Water Alliance.