A warning has been given to the Wellington region that unless it starts looking for a new water supply now, it'll end up in the same crisis as Auckland within the decade.
A business case into household water meters is currently being finalised, following revelations demand for water in Wellington could outstrip supply by 2026.
That's unless an initial 10 per cent reduction in demand is achieved over the next six years in the capital to offset growth over the same time period.
Upper Hutt mayor Wayne Guppy told the Herald every option has to be looked at, including metering, but supply was crucial.
"A new water source has to be on the table and we cannot hide it. We might prolong it for a little bit of time but the bottom line is the models have to include climate change, otherwise Wellington will be in the exact same boat as Auckland.
"We need to make sure that in 20 years we're not sitting around listening to our children saying: Why didn't you guys build a new source when you knew that Wellington needed it?"
A reduction in 40 litres per person per day in gross demand would mean a $250 million investment in a new water source could be deferred.
But Guppy said water metering would also come at a cost because the technology would need to be installed.
A Wellington Water report outlining problems with the region's supply-demand balance insisted the company was not ignoring the potential need for a new source, after pitching metering as an interim solution.
It noted there was "relatively little headroom" available between current demand and the existing system.
It said close monitoring of the supply-demand balance would be needed over coming years as well as initial preparatory work for a new source.
Wellington mayor Andy Foster has landed at the other end of the spectrum to Guppy.
He said the region has three options to deal with the looming supply shortage, which are to reduce demand by metering, increase supply, or change the level of service.
Foster said he was inclined to favour the latter before resorting to metering because of the costs and affordability issues.
"In other words be prepared to accept that in drier periods we're not going to be able to do some things with water like watering the garden", he said.
Under current service expectations Wellington's water supply network should meet normal demand up until a drought is more severe than a 1-in-50-year event.
But this level of service hasn't actually been met since 2017.
Constraints at the treatment plant mean Wellington Water would be unable to meet normal demand from about a 1-in-15 year event.
Porirua mayor Anita Baker said she was in favour of water metering.
"They actually help slow the usage down so people with more family members or people with swimming pools and spa pools who are using more than other people, they're paying for what they use."
Baker said councils sometimes showed reluctance over water metering because elected members worried residents would oppose the move resulting in councillors and mayors getting booted out of office.
"It shouldn't be about an election issue, it should be about saving and conserving the water going forward. Kapiti has done it so there's no reason as a region the rest of us can't get on with it."
Kapiti Coast District Council introduced metering in 2014 and within 18 months peak day consumption decreased by about 26 per cent.
In that same time period 443 leaks were found and 97 per cent of them were fixed.
Hutt City mayor Campbell Barry said he was open to water metering.
But he said it should be consulted on as a region rather than individual councils, which would "take some of the heat out of what is a controversial issue".
"If all councils were to agree to look at it together, it does avoid I think the fear of councils individually going out there and the controversy that has been seen in the past when councils have tackled this issue by themselves."