Auckland sinkhole: Human waste flowing into Waitematā Harbour will 'extinguish' life on sea floor - expert

Watercare apologised to Aucklanders on Monday as it embarked on an emergency bypass build around the sinkhole and its blocked sewage pipe.

Eight of 40 affected sites have returned results for high fecal matter, and one scientist says the millions of litres of human waste flowing into the Waitematā Harbour will be destroying everything in its immediate path.

It may be windsurf weather but take a fall and forget salt water - you could be drinking wastewater as poos from the loos of Parnell pours into the harbour.

"You've got the bacteria, the viruses and other things that are in human waste in the water. They persist in the water for weeks, so there's a risk there because you might swallow it or get it in any orifice," Auckland University marine scientist Professor Andrew Jeffs said.

So most were sticking to the shore today but what about those underwater - snapper and other sea life? For them, this sinkhole and sewage spill is serious.

"Anything that was living there will be extinguished, so you'd expect the footprint around where the pipes emptying into the sea to be basically killing everything on the sea floor," Prof Jeffs said.

"Within a wider radius, it'll be choking any organisms that'll be filter-feeding. Many, many marine organisms filter-feed - mussels, oysters, sponges."

The tennis court-sized sinkhole formed last week when the earth caved in on the sewer 13m below, and creating a blockage.

From above, this red line is the Orakei main sewer, the green line is the new bypass. The aim is to build it within 10 days.

The bypass plan.
The bypass plan. Photo credit: Supplied

"Needless to say, it is our single-minded focus remedying this blockage and preventing the overflows from occurring. So we are working diligently, there are quite literally hundreds of people involved in this," Watercare COO Mark Bourne said.

For now, public health warning signs greet Aucklanders seeking a school holiday soak.

"We are saddened by the overflows and we apologise sincerely to Aucklanders. In my 35 years in the wastewater industry that's my job - to make sure wastewater overflows don't occur. So we're sincerely apologetic about it," Bourne said.

And, with wind forecast, the sand may not be safe either.

"The other risk is just airborne. These particles get blown off the surface of the water so you get droplets containing bacteria, viruses, people breathe them in and you get respiratory illnesses or sicknesses from that," Prof Jeffs said.

"So, given the amount of wind we've had in Auckland over the last few days, there's a real risk within probably a kilometre radius."

And if you've caught dinner off the rocks don't eat it.

"Well, I wouldn't be eating a snapper out of this water," Prof Jeffs said.

Basically, give the beach a miss.