Wellington councils are investigating a seabed back-up supply if the main water pipelines to the capital are cut in a major earthquake.
A plan by Wellington City Council to build the region's biggest reservoir, mostly to supply Wellington hospital after a big quake, is on hold.
But chief asset officer Anthony Wilson says he hopes that emergency water can be fed to the city through a pipe on the seabed, under Wellington harbour.
He says a pipeline could be laid across the harbour from Seaview using technologies developed by the oil and gas industry.
The council had planned the Hospital Prince of Wales reservoir to provide an emergency water supply to the capital's main hospital after a big quake.
Only one week's supply, at normal usage rates, is kept in reserve at the hospital in addition to firefighting water.
In May, the council said construction was planned to be completed by 2017 but a resource consent process failed to start as scheduled in July.
Mr Wilson says no agreement has yet been reached on how much the Capital & Coast District Health Board will contribute to any eventual reservoir at Prince of Wales park.