Raw sewage has poured through an elderly couple's garden in Takapuna and into the Waitemata Harbour.

Noel McCarthy, 85, who cares for his wife Joanne who has Alzheimer's, said their garden in Huron St was flooded with sewage yesterday from about 9am to 1pm.

It was the third sewage spill through the property this year. McCarthy blamed nearby apartments for overloading the sewer line, leading to a manhole on his property popping at high tide and pouring sewage through mangroves into the harbour.

The couple's caregiver, Loretta Devonshire, said the spill was disgusting, leaving toilet paper, baby wipes and condoms strewn across the garden.


She took a video of the spill yesterday.

Devonshire said Watercare Services had been out yesterday and today and done a fantastic job to help the McCarthys. They had promised to disinfect the property, she said.

"Something has to be done. You can't have this running out into the harbour," said McCarthy, a retired French polisher who has lived at the property for 50 years.

Watercare chief executive Raveen Jaduram today said the council water company "would like to sincerely apologise to Noel and Joanne McCarthy for the overflows that occurred on their property".

Jaduram, who has taken a personal interest in the spill after being contacted yesterday by someone who knows the McCarthy's, said investigations had found the overflows were the result of two factors.

"Firstly, we found a telecommunications duct had been drilled through our sewer pipe by mistake by a telecommunications contractor. This created an obstruction in the sewer.

"Secondly, homes and businesses in the neighbourhood have been pouring fat down their drains which had built up around the duct, causing the blockages and subsequent overflows.

"As a matter of urgency, we are undertaking work to remove the telecommunications duct, clean out the fat and repair our sewer. This will ensure there are no overflows in the future," Jaduram said.

He said Watercare had visited the McCarthy's property today to carry out a full clean-up.

"I will personally be writing to them to apologise and explain why the overflows occurred."

Watercare has reminded residents and the hospitality industry not to pour hot fats and oils down the sink as they solidify when they cool down, leading to blockages in private and public sewer pipes.