Porirua City Council is scratching its head on how it's going to meet the costs of a $2 billion bill to bring its water network up to scratch over the next two to three decades.

Photo: 123RF

Wellington Water delivered the news to city councillors in a closed door meeting yesterday.

The council's 2018 Long Term Plan showed more than half of the city's wastewater pipes were in a poor or very poor condition, as were nearly a quarter of its drinking water pipes.

Porirua mayor Anita Baker said many of the asbestos cement pipes installed when the city was built in the mid-1900s were starting to fail - 50 years earlier than expected.

"We've had more water leaks come through after the Kaikōura earthquake, and the cost and compliance to do things has risen.

Despite the unflattering reports, she said the cost of fixing was "a lot higher than expected".

"More of our infrastructure is broken than we realised."

She said the the city had 19,000 ratepayers for 57,000 residents, "so we can't pay all that amount".

"We've asked staff to go back and look at how much we can borrow and what we can fix."

The Mayor said the figure could get worse if residents did not reduce the water they were all using.

All but one of Porirua city's reservoirs are rated D, meaning they're not expected to survive a M7.5 earthquake.

The annual report cautioned that, if there was a large rupture of the Ohariu fault, the city could be without clean water for up to four weeks, and without storage for much longer.

The bill factors in the cost of growth, she said, but does not account for inflation.

"Underinvestment from councils, I have to say, have probably added up for all of us in the region.

She described the report as a wake-up call for councils.

A plague on all councils

Baker said councils throughout Wellington - Lower Hutt, Wellington, Upper Hutt and Porirua - were all facing similar issues and should go together to central government for help.

A plague of issues is facing Wellington City Council's water infrastructure and water quality, and it remains unclear what it will cost to fix the capital's pipe network, or the extent of the issues.

Stuff reported in January that the Hutt City Council will need to spend an estimated $270 million on water services over the next decade if it wants to keep up with growth.

The report showed 60 per cent of Hutt city's water infrastructure needed to be renewed in the next three decades.

Upper Hutt City Council hasn't been given its report yet, but its latest Long Term Plan noted that the Hutt Valley's main trunk pipeline, constructed in 1958, was ageing, and currently cannot be taken off-line for inspection or maintenance.

A major capital project is already planned in 2020/21 at a total cost of $5.3 million - to be shared between councils, will aim to duplicate the main sewer to allow for maintenance in the main pipe and improve earthquake resilience.

"As a region we're all suffering from the same thing and Wellington Water have actually proved that - that's it's been under-investment and it's actually the council's issue, not Wellington Water's," Baker said.

"The problem is the councils don't have the money to pay Wellington Water to do it."

Taskforce is 'finger-pointing'

News of a taskforce in Wellington to tackle Wellington's water issues is an attempt by local politicians to hold everyone but themselves accountable, according to the Wellington Chamber of Commerce.

Wellington Mayor Andy Foster yesterday announced a taskforce would investigate the state of the city's water infrastructure, investment provisions, maintenance, and governance of the region's water management agency, Wellington Water.

Wellington Chamber of Commerce boss John Milford said the taskforce was a cop-out from councillors who he claimed had failed to invest properly in infrastructure.

"Despite significant year-on-year rates increases, capital expenditure on core infrastructure keeps being delayed and deferred meaning decades of under-funding.

"That's not the fault of officials. That's on the politicians. It is only with sewerage now flowing into the harbour, that councillors are finally getting serious.

"Finger pointing by the council is not good enough. The council owns the pipes, and it is the councillors who sign off on all funding and investment decisions."

At the time, Foster said taskforce would be a useful tool for meeting expectations that the community, mana whenua and council had on clean water and environmental protection.

News of the taskforce came hours after the majority of councillors backed a call for a wide-ranging inquiry into Wellington Water.