As raw sewage closes Wellington coast, sludge plant hits further problems
Thursday, 5 February 2026
With about 70 million litres of untreated sewage spewing daily into the Cook Strait, and beaches closed at the height of summer, Wellington City councillors are being warned of critical issues in the new plant right next door.
A grim-faced Wellington Water chief executive Pat Dougherty, with Wellington mayor Andrew Little, fronted to the public on Wednesday and outlined the catastrophe that continued to play out at the Moa Point sewage treatment plant since starting at 1am that morning.
Wellingtonians will be unable to use the south coast beaches for the next few weeks, and possibly months, by which time the city’s brief window of warm weather will be over. The cost of solving the problem was as yet unknown.
The 1800m long outfall pipe that sends treated wastewater deep into Cook Strait backed up for reasons unknown. It “completely flooded” the lower floor of the Moa Point plant with wastewater, tripping all fuses.
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“We have a scrubber room at the bottom of the plant,” Dougherty said.
“It's the size of an Olympic swimming pool, and it’s three metres deep in wastewater.”
Dougherty said some equipment could take months to repair.
“Some of it will probably be a write-off, and we may not be able to source from within New Zealand.”
The long outfall pipe could not be used as it needed pumps, so untreated wastewater was being diverted to the 5m pipe into Tarekana Bay, east of Moa Point.
It would be a “few days” to get the long outfall pipe going again, which would see the waste going through some screening.
At the peak, 3300 litres of wastewater per second was going into the short pipe but that was mostly rain. The normal flow expected over the coming few days was 70 million litres – equivalent to 28 Olympic swimming pools – a day.
It would be a few days before people could return to South Coast beaches but “don’t go in the water”, Dougherty said.
“We will be carrying out any monitoring that the regulatory authorities want. But I think the biggest impact is going to be on Wellingtonians being denied use of the south coast for the next few weeks, if not months.” Dougherty pledged to make the monitoring readings public.
On Wednesday night, Wellington Water said the sampling area had been increased to stretch from Breaker Bay to Seatoun. “While we understand the risk of wastewater reaching from Tarakena Bay around to Seatoun to be very low, we are erring on the side of caution and completing sampling at these sites every 24 hours.”
Coming at the end of summer, Little said it couldn’t have come at a worse time for the south coast – the harbour was considered safe except for standard warnings about staying out of the sea after heavy rain.
“Plan not to swim. Plan not to go on to the beach,” Little said.
“Don't take your dog onto the beach. Don't let the kids play on the beach. The risks are too high.”
Taranaki Whānui chief executive Kara Puketapu-Dentice told RNZ the situation was unacceptable.
“It is like we have got Third World infrastructure in a First World country and our environment is suffering because of that.“
The Department of Conservation warned that mussels, kina, pāua, sponges, fish, and penguins could be at risk, RNZ reported.
Greater Wellington Regional Council chairperson Daran Ponter was “livid” about the situation, which could affect communities for months. The council’s environment team was investigating.
“Wellington summers are over in a flash at the best of times, so people will be naturally frustrated with the last of their holidays and access to the beaches and sea being curtailed.”
Wellington City councillors will meet on Thursday morning greeted with that sobering news and more.
The under-construction sludge treatment plant being built alongside the existing Moa Point facility has been put into “red” high and critical status due to electricity and construction issues.
The sludge plant – which was going to cost $200m in 2021 then $511m in 2025 – was designed turn wastewater into almost-odourless pile of pellets which could be reused in gardens. It was designed to be a second process after the flooded plant.
Now Wellington City councillors are being told the project has an overall “red” health rating – the worst of a three-step rating system.
Wellington Electricity supply issues were “critical” as their completion was required for commissioning of the plant to start. Teams were working on “temporary options” while permanent upgrades were undertaken.
“High risk” issues had been found with some steel used in the main process building not meeting design requirements. Independent structural engineers were now looking into whether remedial work was required.
“It may have programme implications”, the report says.
There were also issues with the facade and roof installation could have “programme implications”.
The project’s completion date has now been moved form February 2027 to April 2027.
A council spokesperson the issues relating to power supply had been dealt with and were “no longer having an impact on the construction programme”.
Regarding the steel, the design specifications required sourcing of steel via an appropriately accredited supplier. “An independent forensic investigator is conducting tests to validate that the steel is compliant with the specifications although purchased from a different supplier,” the spokesperson said.
But there is a ray of good news: The forecast overall cost has dropped from $511m to $483m.
It appears some of those savings come from Government resource management changes that mean Wellington’s treated sewage can continue to got to the landfill for longer rather than being trucked to the central North Island.