Watercare says it could take at least three days to unblock a damaged underground sewer pipe in central Auckland, with millions more litres of wastewater potentially flowing into the Waitematā Harbour. 

The organisation’s chief operating officer Mark Bourne told the AM Show that he is aware of three locations where wastewater is flowing into the Waitematā. 

“There are two locations near Mechanics Bay that commenced yesterday afternoon, and yesterday evening we monitored a third location towards the western end of the Viaduct Harbour,” Bourne said. 

A main Auckland sewer line has collapsed, causing a massive tomo (sinkhole) to open up, with wastewater overflow pouring into the harbour and closing 25 city beaches on all sides of the harbour. 

The 13-metre-deep hole descends to a 2.1m-wide collapsed brick pipe below a private property on St Georges Bay Rd in Parnell that serves central Auckland and West Auckland. 

The sinkhole on St George's Bay Rd is the size of a tennis court. Photo / Facebook 

Bourne said crews have been working overnight to unblock the pipeline. 

“Once the pipeline is unblocked and it can return to service and that will prevent the overflows from returning,” he said. 

“Then we can get on with the repair ourselves.” 

He classified the quantity as “a large overflow”. 

As much as hundreds of litres per second of wastewater was spilling into the harbour. 

“That’s why we’re asking people not to swim, fish, or do watersports in the Waitematā Harbour, as all of the beaches have been black-flagged,” he said. 

Parnell Business Association general manager Cheryl Adamson said the collapsed pipe “comes as no surprise”, saying overflowing sewage has plagued properties for years. 

“Watercare’s inability to address a number of issues our businesses have had, some dating back to 2021, has us all very concerned,” Adamson said. 

“Business owners have suffered enough. Businesses in Watt St had sewage water into their premises earlier this year. Along The Strand, certain businesses who have relocated back after the January floods complain about unpleasant smells in their bathrooms after heavy downpours,” she said. 

“We’ve been calling on a resolution for a long time, with this collapsed pipe being one of many signs that the water infrastructure systems in Parnell are in dire need of support.” 

Safeswim’s website shows all beaches west of St Heliers and several on the North Shore in Auckland are closed. Photo / Safeswim 

Bourne said they will be taking water quality samples during the overflow and once it stops. “Typically, it is safe to swim from between 48-72 hours after an overflow is stopped.” 

Auckland deputy mayor Desley Simpson told TVNZ’s Breakfast this morning the council was working round the clock to fix the sinkhole. 

Crews had been working through the night, pushing “a huge amount of water” through to clear the blockage. 

“They’re going manhole by manhole to try and clear it.”