A major upgrade of Colac's main water supply pipeline is nearing completion.
About 5.4 kilometres of pipe have been replaced, with a further 800 metres remaining.
Barwon Water General Manager Capital Projects Paul Northey said work on the $14.7 million project had been slowed by wet weather.
"We had hoped to complete the major portion of works by the end of August, but the weather has pushed the finish date out to October," Mr Northey said.
"Extensive road maintenance and innovative construction techniques have allowed work to continue albeit at a slower pace."
He some minor works would be undertaken during the drier summer months.
The upgrade will increase capacity and ensure supply security.
Bypass stations have been installed to ensure there is no interruption to Colac's supply during construction.
The 28-kilometre pipeline, which connects the West Gellibrand and Olangolah reservoirs to Colac, was constructed in 1910.
The upgrade is part of a staged replacement plan, with the first sections of the program completed between 2002 and 2007.