The need for an alternative water supply source for Wellington city has long been recognised. This need was heightened by the Canterbury earthquakes of 2010 and 2011 and more recently the Kaikoura earthquakes.

A range of different options for an alternative supply have been investigated including a desalination plant and using harbour bores to tap into the undersea section of the Waiwhetu Aquifer.

The Cross-Harbour Pipeline was confirmed as the best option late in 2018 following a programme of drilling two exploratory bores into the harbour floor. Tests from these bores showed that water quality and quantity from the undersea aquifer was not suitable to meet our water resilience goals. Additional investment would also have been required to treat water from the bores.

However, as a scientific project, the exploratory bores have provided invaluable data about the harbour seabed and the aquifer, helping inform development of the Cross-Harbour Pipeline and ongoing management of the area.