A water management report has warned of future Wellington water shortages if usage and population growth trends remain the same.
A report from council-owned company Wellington Water, which manages water assets for five councils in the region, found if residents kept hosing their gardens and showering like they did now, demand for water would exceed supply in 2040.
The report, discussed by some of the region's mayors and councillors during a Wellington Water Committee meeting on Monday, was a starting point for discussions that would include councils and residents, Wellington Water's group manager for network strategy and planning, Mark Kinvig said.
Wellington Water looked after water assets for the Wellington, Upper Hutt, Hutt City, Porirua and Greater Wellington regional councils.
The report identified three key issues, Mr Kinvig said, the first being that demand for water would exceed supply.
"We know that from our modelling work, and that modelling work takes into account growth and climate change.
"Secondly our water sources and network are vulnerable to earthquakes and climate change as well, in terms of storms, and rising sea levels."
The third was there could be less water available in aquifers and rivers due to tougher environmental rules.
The next step for the organisation is to understand those issues better, then work with councils to come up with solutions. These could include educating the public, a new source of water or more storage, and keeping on top of leaky pipes.
Wellington Water Committee member, councillor Iona Pannett, said potential solutions, like a new dam or water metering, could be contentious.
The committee, which is made up of the region's mayors and councillors, oversees Wellington Water.
"We haven't come up with any definite answer about what needs to be done, but at the very least we do need to start with public education," Ms Pannett said.
Water meters were brought up last year by Greater Wellington Regional Council chairman Chris Laidlaw, after an unusually hot summer saw restrictions enforced across the region earlier than usual.
Mr Laidlaw said it was inevitable meters would be introduced and that these would be likely part of a national approach to managing drinking water.
"There's no question that metering produces savings," he said.
"There are some people who say 'well I don't like water metering because in effect this is the first step towards privatisation'.
"There's no link between water metering and privatisation at all."
The debate around water meters needs to be kept open, he said.
In the meantime, with whatever solutions were found, residents would have to do their part, Mark Kinvig said.
"This is not just down to the actions that we take, and our client councils take. Every Wellingtonian has a role to play to use the region's water in an efficient way."