Watercare says the new watermain is known as the North Harbour No.2 Watermain.
The watermain will run from the proposed new storage reservoirs at Woodlands Park Road in Titirangi via Hobsonville and Greenhithe and to the exiting Albany storage reservoir on the North Shore.
The new 33 km pipeline will have a 12 m diameter from the Woodlands Park Reservoir, and a 910 mm diameter from the Greenhithe Bridge to the Albany Reservoirs.
Trenchless solutions are proposed at the southern extent of the route associated with key rail, road and motorway crossings.
The current program is to begin construction in 2018.