Paihia's water treatment plant was also damaged and residents are being asked to conserve water over the next 24 hours.
There are also power outages at Taupo Bay, Kaeo, Matawaia and Hihi.
Bay of Plenty Regional Council rivers and drainage staff are also busy responding to flooding-related calls including over-flowing drains, streams and canals.
The Bay of Plenty District Health Board has warned that people should avoid swimming in all rivers, streams and harbours for 48 hours as farm run-off may have contaminated them with sewage. Sewage overflows have also been reported in Tauranga Harbour and residents were urged to conserve water for the next 24 hours.
The Far North and Whangarei district councils are trying to repair all road damage today and return everything back to normal.
State Highway 1 is open to Warkworth and the northbound tunnel at Puhoi has been re-opened, and there is a large amount of slow-moving traffic on the road, police say.
Diversions are in place at Warkworth, taking northbound traffic to State Highway 16.
The northern region fire communications centre has responded to more than 350 weather-related incidents throughout the Northland, Auckland, Waikato, and Bay of Plenty regions since 6pm yesterday.
Earlier this morning, firefighters used a boat to rescue a man and woman stuck up trees in Pipiwai, 43km northwest of Whangarei, for more than three hours, due to the rising flood waters.
Also safe were two people who had been believed missing after a house collapsed when it was hit by a large slip at Onetangi, on Waiheke Island, this morning.
In Kaeo, 111 communications centre staff were in constant contact with a family trapped in their house.
"Two adults and two children became trapped in flood waters. Water rose to above eight feet (nearly 3m) to the level of the house's veranda. The back of the house started to slide away as waters eroded a bank," Fire Service northern communications spokesman Jaron Phillips told NZPA.
Firefighters also attended an incident where a car went into a river in Wilson Road, Parakao, 40km west of Whangarei.
Other incidents included a rescue in Whakapara, 23km northwest of Whangarei, after a car became stuck in flood water. Three adults and a child roped themselves together and were rescued by firefighters.
On SH1 at Okaihau, 63km southeast of Kaitaia, two people become trapped and were forced to cling to logs as floodwaters rose. Firefighters used a dinghy to rescue the pair as water levels rose quickly.
In Stanmore Bay, 40km northeast of Auckland, a landslide crashed into a house.
Police were being inundated with calls about slips, road closures, trees over roads and surface flooding from Maunganui to Warkworth, police northern communications shift commander Shawn Rutene said.
The severe weather was moving towards Tauranga, Whakatane and Awakeri, and the bridge between Tauranga and Mt Maunganui was closed.
People in Rotorua were also being urged to stay at home and only travel if necessary, as flood waters are blocking a number of roads around the city centre.
SH5 north to Hamilton is closed by a slip about 100m north of Tarukenga Road near the Lakeview golf course. The Utuhina Stream is in flood and getting close to the point of bursting its banks.
The MetService said Wilma should pass just to the north of East Cape late this morning before racing away to the southeast.
- NZPA
