Wellington sewage spill: ‘Crazy’ blowflies in Lyall Bay as rain again threatens Moa Point sewage plant
Wednesday, 11 February 2026
The first deluge of raw sewage off Wellington’s south coast brought bad smells, a drop in business, and “crazy” flies – and now heavy rain threatens a sequel.
In fact, the Moa Point catastrophe has been running continuously since early last Wednesday morning but, after the initial few days of sewage dumped 5 metres off the coast, it was diverted 1.8km further out, still untreated.
The sewage treatment plant had a catastrophic failure early last Wednesday when sewage, mixed with a heavy load of rain water, reversed in the 1.8km outfall pipe – meant to deliver treated wastewater deep into Cook Strait – inundating the plant in 3m of dirty water.
The cause remains unknown.
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Now heavy rain is threatening to return on Sunday and Monday, meaning the shorter pipe may have to be used again.
Along the south coast on Wednesday – a week on from the start of the fiasco – crews were warning people to stay out of the water and keep off the beaches, where sewage can wash up. Earlier warnings were issued that the water may be off-limit for months.
At one Lyall Bay food outlet, not far from the end of the 5m or 1.8km pipe, workers said business was down significantly.
“The flies around here have been crazy – big blowflies,” the worker said.
At Queens Drive Dairy, at the other end of Lyall Bay, Jay and Gita Parbhu said business was down about 60% and they had started closing an hour earlier.
“A lot of people are saying fix it as soon as possible,” Jay said. “It looks like a big job.”
Metservice meteorologist Mmaphapelo Makgabutlane confirmed a low pressure system was looking like forming north of New Zealand and it was “very much in the realm of possibilities” that it would track near Wellington on Sunday and Monday.
It had the potential to reach heavy rain warning levels – up to 100mm of rain in 24 hours hours or 50mm in six hours.
On the night of the initial breach, 33mm fell from 6pm Tuesday to 3am Wednesday,
Wellington Water appears to have only inspected 300 to 600m of the 1.8km pipe.
The utility has been asked if there is a risk of a repeat, plant-flooding disaster if heavy rain hits this weekend.
It was also asked what precautions it was taking for heavy rain. It previously said that raw sewage may have to again be discharged just off the coast in heavy rain.
Meanwhile, in a statement on Wednesday, Wellington Water said it continued to remove “biological material” from the plant.
“Fresh water is being flushed through the biological treatment areas of the plant to reduce levels of hydrogen sulphide, which makes the interior of the plant hazardous to enter.”
The full impact of the flooding on the plant was still unknown but an extended outage was expected.
“Odour complaints have been received, and odour levels will be more noticeable while the plant odour and ventilation equipment is offline and screening is working in a temporary configuration. Odour will also be present during the removal of sludge from the plant,” the statement said