Heavy rain that began on Wednesday night started to ease on Friday morning. Falls in the Great Lake region were the highest, with 398 millimetres in 30 hours.
Evacuation orders are in place for people living along the swollen Mersey and Meander rivers, downstream of Lake Isandula dam and in the Launceston suburb of Newstead.
There is also a move-to-higher-ground emergency warning for the St Patricks River.
"This is actually the danger period. Our messaging to the Tasmanian public at this point in time is don't be complacent," State Emergency Services acting director Leon Smith told the ABC on Friday.
"All of that rain that's fallen at the higher altitudes still needs to make its way down through the riverine systems. This flooding will be sustained."
Mr Smith said it would take several days for waters to subside.
Emergency services rescued a family of six who became isolated on their property, while a man and woman were helped to safety by helicopter after driving through floodwaters in their 4WD.
Authorities have warned river peaks in some parts could reach levels seen in mid-2016 when flooding claimed three lives and caused $180 million worth of damage.
Peter Freshney, mayor of Latrobe Council which sits along the Mersey River, said some properties had been inundated ahead of an expected flood peak on Friday.
"At this stage (the flood level is) below 2016. We'll see what happens when the peak arrives. There's still a bit of anxiety about that's for sure," he told AAP.
"The river is flowing really rapidly. There's a lot of debris, trees and the like."
The SES issued an emergency evacuation alert on Thursday night for 42 homes south of the dam at Lake Isandula after being advised it was at risk of failure.
The dam is now considered stable. A full assessment will be undertaken on Friday.
About 70 homes in Newstead were also evacuated overnight, with the SES receiving 147 calls for assistance from flood-hit areas.
Thousands of customers were without power across the state on Friday morning and some could be cut off for days.
Five people and their animals were rescued from a property at Liffey, southwest of Launceston, on Thursday.
Evacuation centres have been set up at several locations.
Tasmania Police has urged people to avoid travelling unnecessarily and to not drive through floodwaters.
31°C