Work is expected to be completed on May 3.
Waters capital delivery team leader Dominika Biziak-Kochan said the project, costing $411,000, would use rock and other stabilising material to rebuild the river bank.
He said flooding in 2017 and 2018, as well as recent heavy rain, had eroded the section of the bank which supported the water pipes.
Work would need to be done urgently.
"This is critical infrastructure. One of the pipes is the sole source of treated water to North Taieri."
He said work would be carried out with minimal impact on the environment and extensive replanting would be done.
"We thank the public for their co-operation while this work is being done and we will work hard to have it completed with as little disruption as possible."