Fatbergs 'a big problem' for NZ's sewers - Watercare

A build-up of fat in a sewer that caused a sinkhole in Dannevirke.
A build-up of fat in a sewer that caused a sinkhole in Dannevirke. Photo credit: Tararua District Council / Supplied

Watercare say build-ups of fat, grease and oil known as 'fatbergs' are "a constant battle" to keep under control in New Zealand's sewage systems.

The comment comes after a sinkhole opened up in Dannevirke, in response to a sewer pipe failure caused by a mass of fat as well as rats, who had been feeding on it.

But Peter Rogers, Watercare's manager for asset protection, said it's not an isolated issue, and said they're now actively trying to educate people on what can and can't go down their drainpipes.

"It's a big problem. It's a constant battle," he told RadioLIVE's Morning Talk with Mark Sainsbury.

He says the popularity of wet wipes is also causing plenty of issues for them, as they combine with the oils and fats to create "massive blockages".

"They block our pumps, so our pumps stop and that can leave to overflows in our network, which is a big problem," Mr Rogers said.

He added that when there is a build-up, Watercare deploys a trade waste team to "jet out a lot of the fat", which ultimately hits the taxpayer in the pocket.

When asked whether wet wipes should therefore be considered flushable, Mr Rogers said Watercare would probably suggest they're not.

"We've not found one [wet wipe] that breaks down like common toilet paper. I mean, physically, yes you can flush them down the toilet, but it causes big problems.

"It's a big cost to home owners when they get blockages in their private line, and it's a big cost for us which again, is really the ratepayer that's paying it."

However Mr Rogers says if everyone is responsible with what they put down their drain systems, there is no reason to fear the fatberg.

"It's a matter of everybody being responsible and disposing of your fat stalls and grease appropriately," he said.

"Scrape your plates and put it into your solid waste, pour your waste into jars or containers and put it into the solid waste.

"We don't have to put up with this problem."

Mr Rogers says he's headed to Waiheke Island with a special taskforce to identify the cause of a fat build-up in their sewers, and to educate locals on how to avoid further blockages.

He says Watercare have education programmes at commercial businesses like food outlets and industrial premises to teach them which waste can and can't go down there.

"When new businesses start up… there are requirements they put in grease traps and we ensure they're sized properly and maintained appropriately," he said.

"We will then go out and investigate what the cause is, and in those cases where we find that premises aren't appropriately managing the grease traps, we put them under active management - so we'll monitor them a lot more closely."