But the failure of the census website to collect information from millions of households on Tuesday night is a hammer blow to public confidence in, arguably, the bureau's most important survey.

No census data has been lost, says Minister Michael McCormack, despite the ABS being forced to close its on-line census site.

The federal minister responsible for the ABS, Assistant Treasurer Michael McCormack, said the website was shut down after co-ordinated attempts from offshore to "frustrate the collection of data".

One of the many troubling questions raised by the inability to deal with those predictable attacks is: can the 2016 census be salvaged?

That depends on how the huge number of households denied access to the census website react.

The bureau's chief statistician David Kalisch said 2.3 million households completed the census online before the outage and about 3 million requested paper census forms. 

But that means about 4 million households will be filling in the census late.

While Mr Kalisch says there's still "plenty of time" to fill in the census, some households may now boycott it following Tuesday night's shambles and questions raised about the security of data.

The flood of bad publicity might also discourage people from being completely honest about sensitive personal information such as their level of income.

Labor's shadow assistant treasurer, Andrew Leigh, claimed on Wednesday that this year's census data would "never be as good" as those held previously because of Tuesday night's debacle.

Dr Ben Phillips from the Centre for Social Research and Methods at the Australian National University said the integrity of the census relied on a very high participation rate.

"It's not like getting a 90 per cent response rate is good enough in a census, as it may well be in another type of survey," he said.

"You want to have almost everyone filling it in - well over 95 per cent. And you want people filling it in honestly, so they provide their proper income, their proper age and so on. 

“For a census it's all about getting that fine, local level detail for small areas ... there's certainly a big risk that the census is in considerable trouble."

Inferior census data would have lasting consequences. The national demographic snapshot taken every five years is more than a population count - it is crucial to understanding how our society is changing.

It provides information fundamental to our democracy because census figures are used by the Australian Electoral Commission to come up with fair electoral boundaries.

The census is crucial for the planning, administration and policy formation of federal, state and local governments. It's especially important for the fair distribution of federal funds across the nation. 

Population estimates, based on census data, are used to determine the allocation of about $50 billion worth of GST funding to the states and territories.

In the past, the ABS has provided guidance to other countries about how to stage censuses. 

But Australia's standing as a world leader in this field must now be in tatters.