The $10m project is intended to build resilience, additional capacity and flexibility into the district's drinking water supply.
Mayor Sandra Hazlehurst said the mains water pipe was a vital part of the council's water strategy, which was focused on making improvements to the district's urban drinking water system.
"This is a very, very important connection that will carry water to Havelock North.
"The council will be careful to keep inconveniences to a minimum, and we must thank residents for their patience throughout this project".
Residents and business owners have been advised of the route this week and community meetings will be held once a contractor has been chosen. The wider public will be advised using traditional and online media.
Trude Weekes of Planters Nursery said she hoped the development would not affect their business or others in the area. The construction will not be on the St Georges Rd stretch where the nursery is, but nearby.
"It's hard to know. I imagine it would be, its a huge volume of traffic that comes along St Georges Rd," she said.
She hoped it would not suffer the same delays as the construction up on Te Mata Rd, "because I've seen how chaotic that's been".