The wild weather left a family trapped with only cheese and crackers to sustain them until their neighbours came to the rescue.
Greg Walker and his partner live rurally near Tauranga, and currently have the in-laws staying with them.
They've been trapped together all day, after a usually gentle stream on their property turned into a raging torrent and isolated the house.
Walker said he realised something was wrong when he woke up to the sound of a heavy downpour.
"We live in a corrugated iron house so it sounded like a freight train, which woke us up around 5.30 this morning.
"I walked outside and immediately knew there was a problem, because I could hear the river roaring from about 400m away.
"We've lived in Cyclone Alley in Western Australia, so we know what floodwaters do, and not to go out in it.
"There was just way too much power in the water, you could barely stand up in it, let alone pass it."
With nothing for it but to wait it out, the four of them spent the day watching the rain fall.
There wasn't much food in the house until their neighbours came to the rescue.
"We just had to survive on bread and water, as well as some cheese and crackers.
"But then our neighbours were kind enough to come down and meet us at the other side of the river.
"I had to carefully wade through to get to them and get some supplies. So it was neighbourly love."
The neighbours brought meat for the barbecue, and some potatoes.
But the prize of the supply drop was "a box of beers, which never goes astray".
The river has now dropped by about half a metre, but Walker still doesn't trust it to try and get through.
Once it drops further, it will be a case of assessing the damage it's left behind.
"That sort of power coming through, it can create new paths, it can collapse banks.
"But realistically we won't be able to assess the damage until the morning."
Those in central North Island areas are being warned to keep survival items nearby, as ex-Cyclone Debbie continues overnight.