The premier was heartened by the response of the community while visiting the flooded southern border town of Moama, where volunteers and locals have built a 200,000-sandbag-strong levy to protect properties from the surging Murray River.
"Mates, local community, people coming together to help every person through this difficult time I think really sums up what is great about the Australian spirit and great about our country," he said on Wednesday.
There are around 100 flood warnings and 43 disaster-declared local government areas across NSW, as floodwaters slowly recede and the focus turns towards the massive clean up.
Earlier, while speaking to reporters at the nearby Deniliquin emergency operations centre in the southern agricultural Riverina region, the premier said the losses were heartbreaking.
"(Farmers) have gone through a bloody tough time for four years.Â
"We've had droughts and now facing what would be a bumper harvest for many will be lost because of this flooding," Mr Perrottet said.
Many homes were also "severely damaged" and the cleanup was going to be challenging.
"It's tough, but ... everywhere I go ... I see a really strong sense of community, optimism, strength, and that's the Australian way," he said.
He was moved by the number of volunteers coming from around the country to help.
"That is the great spirit of Australia and .... that instils me with the hope and understanding and knowledge that we're going to get through it just like we got through everything else."
At Moama Mr Perrottet said he had been in close contact with Victorian Premier Daniel Andrews to offer "whatever support he needed".
Co-operation between governments and state agencies was closer than ever.
"To see federal, state and local government agencies .... all working together I believe puts us in a very strong position to deal with the challenges that are coming our way," he said.
Deputy Premier Paul Toole says the long-term consequences of the crisis are not yet clear.
"We probably won't know the full extent of it until the waters do recede and to actually see whether or not farmers can get onto their paddocks and actually make any use of the harvesting that's available to them," he said.
Flood Recovery Minister Steph Cooke warned while conditions were easing, her department was watching a weather system expected to cross the state on the weekend.
"We are very much watching river systems right across the state, particularly inland at present," she said.
Ms Cooke praised the roughly 700 State Emergency Service personnel in the field, and says Australian Defence Force troops are still helping.
"They just keep getting up day after day after day and working with communities and lending that support ... where it's needed," she said.
Ms Cooke said they now had one eye on the recovery process.
"As soon as floodwaters do recede, then we will be able to get in and do those rapid damage assessments and look to get communities back on their feet as quickly as possible."
The premier flew to Moree in the far north on Tuesday where thousands of residents are under evacuation orders after the Mehi River reached major flood levels.
A clean up has begun with people pulling rubbish from their waterlogged homes.
The Bureau of Meteorology expects thunderstorms to develop across eastern NSW on Thursday, with a possibility of becoming severe.
Falls will persist on the coast into Friday, before warmer and drier conditions develop into the weekend, BOM's Jonathan How said.
Major flooding continues in multiple towns including Echuca, Moama, Barham and Kerang on the NSW-Victoria border, Moree, Gunnedah and Narrabri to the north, and Hillston, Hay and Condobolin in the west.
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