Fire chiefs have expressed exasperation at community apathy and failure to plan for a bushfire, which could mean overwhelmed shelters.

According to CFA statistics, three quarters of people living in bushfire-affected areas don't have a fire plan.

CFA Nillumbik community safety manager Helen Kenney said the figure is much higher and many private properties were a fire risk.

There are six NSPs in Nillumbik but they can only cater for a limited capacity.

"They're not factoring NSPs into a plan, they're totally reliant on them, they're not making a plan. People still have gutters full of foliage," she said.

She said the low attendance rates at CFA community fire sessions was also worrying.

"It's almost become the 'boy who cried wolf' syndrome, people are not turning up to community fire ready meetings. They're just not listening," she said.

CFA Eltham operations officer Tony O'Day said too many residents were relying on a NSP instead of preparing a fire plan.

He said it was difficult to estimate how many people each NSP could shelter but they would not cater for all who sought safety.

"NSP are not plan A, they are plan S, that's the key message for people. We only have a finite amount of vehicles and people, so the thing about NSP places is whilst we plan on accommodating people in it, we truly don't know what will happen," Mr O'Day said.

Nillumbik council spokeswoman Joanne Hammond said residents must remember that most NSPs are outdoors and there was no guarantee a fire truck will come to the NSPs. She said residents needed to seek advice from the council and CFA.

Ms Kenney said: "You can get a CFA home inspection to assess your property. They can give you hints on how to improve safety. " she said, urging residents to contact Nillumbik Council, "they're an under-utilised resource."