A red flag was raised about Wellington's poor water infrastructure and the billions of dollars needed to fix it as early as 2014, during plans to amalgamate the region's councils.
The Local Government Commission ordered a report into the financial impact of replacing pipes in the region made out of asbestos cement, or pipes in poor or very poor condition.
That bill was estimated to be as high as $2.6 billion for these wastewater and water pipes. Stormwater pipes were not included in the calculations.
The outlook for Porirua City painted in the 2014 report was particularly grim with 84 per cent of its wastewater pipes in poor condition or made from asbestos cement, and 61 per cent of its water pipes.
Current city councillors and mayor Anita Baker have recently been briefed by Wellington Water that they need to spend a whopping $1.8 billion over the next 30 years to get Porirua's pipes up to scratch.
The situation has been exasperated by asbestos cement pipes failing prematurely.
Well-installed pipes should last as long as 100 years but it's now known the average life of asbestos cement pipes is closer to 50 years.
NZ Herald analysis of current Wellington Water data showed Porirua City has the highest proportion of asbestos pipes in its three waters network compared to the rest of the region's territorial authorities.
A third of the city's stormwater, wastewater and water pipes are made from the material.
Meanwhile, only 12.9 per cent of Wellington City's pipe network are made from asbestos cement.
Water New Zealand technical manager Noel Roberts told the Herald the lifespan of pipes made from this material wasn't understood when they were first installed in the 1950s.
"I don't think anyone knew when they were installed exactly what the life expectancy was … we're in that technology knowledge bubble where in some cases we're working out things on the go."
Asbestos cement was popular because it was cheap and could be manufactured in New Zealand, he said.
But their popularity has now become a budgeting issue for some councils.
"It's caught them out because it's failing earlier than they were starting their tests or they've only done one or two assessments and are going 'oh my god'", Roberts said.
Manufacturers stopped producing pipes made from asbestos cement in the 1980s.
In 2018 Timaru District Council forked out $3.3m to replace 9.1km of water main made out of asbestos cement supplying the small town of Temuka.
The "progressive internal failure" of the pipe created higher than usual asbestos readings in the water, which raised the red flag.
Asbestos cement pipes degrade in a linear manner unlike ceramic pipes, which are fragile, but aren't constantly deteriorating.
There were several different manufacturers of these pipes and some were failing at different rates to others, Roberts said.
It also depended on water pressure and thickness of the pipe, he said.
Wellington Water chief executive Colin Crampton said significantly more money would need to be invested in the region's water network in the years ahead.
The organisation wanted to fast-track pipe condition assessments over the next three years to build a better picture of necessary renewals, he said.
"So that everyone can be reassured that we are making sure we are investing in the right places and also to prevent any unexpected failures happening again."
Typically less than 5 per cent of the network Wellington Water managed on behalf of councils was assessed annually, he said.
Crampton stressed that just because pipes had reached their average life expectancy, didn't necessarily mean they needed to be replaced.
Some pipes in the network were more than 130 years old and in working condition, he said.