Wellington's deputy mayor is warning it could cost every ratepaying household or business more than $80,000 over the next 25 years to fix the city's poor pipes alone.
Ben McNulty said figures - first highlighted by Wellington Water - that it would cost over $6 billion to fix Wellington city's pipes over two decades, would put enormous pressure on residents - and more government support in the future would be needed to ease bills.
McNulty said taking the $6b cost and dividing that by 81,000 resident and business ratepaying units revealed a concerning outlook.
"It's just not affordable. It is beyond the capacity of ordinary people to pay."
Water agency Tiaki Wai declined an interview request, even as the cost figures swirled on the campaign trail with Wellington candidates discussing it.
A spokesperson did not respond directly to McNulty's numbers, referring to a previous media release which stated a 13.3% increase in water bills for this financial year.
McNulty said poor pipes were only a portion of upcoming costs for the city and region, which also needed to address stormwater infrastructure in floods, and safe drinking water.
"All we're talking about is what it costs to fix the infrastructure in a poor or very poor condition, not even counting what it costs to maintain the water network, to fix leaks, to ensure that there's sufficient water storage or other needs," McNulty said.
The issue of Tiaki Wai charges has been a major one for the region, with household bills expected to reach over $6000 per year in a decade and prompting protests in central Wellington.
The water agency had previously signalled it could cost up to $25b over 30 years to fix the failing infrastructure across the entire region.
McNulty said Tiaki Wai's plan to replace between 35 and 49 kilometres of pipes in its first year was a good start, and 3-4 times more than what previous organisation Wellington Water delivered last year.
He said a "fairer funding system" was needed.
"When it's that unaffordable, the government has to at some point to come to the party because Wellingtonians can't afford to fund [the costs] single-handedly."
McNulty called for the government to co-invest in major water network projects in Wellington, to secure drinking water supply and protect from "major failures".
He said the Commerce Commission should have price-quality control over the agency and that the Crown should help secure water-sector debt, to lower borrowing costs.
Tiaki Wai told RNZ it wouldn't comment on party policy.
In a statement provided on Friday to separate questions, chief executive Michael Brewster said after decades of under-investment, it was vital Tiaki Wai collected revenue to fix ageing water networks.
"We understand people in Wellington are facing cost-of-living challenges, so we're offering flexible options for those in hardship."
Wellington candidates support government funding
McNulty's comments came as Wellington Bays' candidates from across the political spectrum said they would support forms of Crown funding into Wellington's water infrastructure.
The government's Local Water Done Well policy did not include government grants for council water projects. The amounts which water agencies could borrow had been extended.
Act deputy leader and Wellington Bays' candidate Nicole McKee said the party would be open to requiring Wellington's funding allocation in its proposed Local Tourism Dividend to go first to fixing water infrastructure.
National candidate Karunā Muthu, and Labour's Craig Renney both said they would advocate - if elected - within government for additional Crown funding for the capital's infrastructure to lower bills.
The Greens' Julie Anne Genter said the government should secure debt to reduce borrowing costs, and the party would be "open to" additional funding tools.
Opportunity's Kayla Kingdon-Bebb said Opportunity would allow councils and council organisations to apply to the Infrastructure Commission for grants or loans.
Senior government minister and Hutt South MP Chris Bishop referred questions on the issue to Local Government Minister Simon Watts.
Watts said it was not National Party policy to be contributing Crown funding.
