"These kids have no stability": Father Chris Riley.

"These kids have no stability": Father Chris Riley. Photo: Greg Totman

The rate of youth homelessness has been grossly underestimated, with thousands of ''couch surfers'' not included in official figures.

The Australian Bureau of Statistics identified 26,224 people aged 12 to 24 as homeless in 2011, but this does not include those who stay with friends or extended family rather than live on the streets. ''Neither the ABS nor other researchers have been able to establish a robust method to more reliably estimate homeless youth staying with other households,'' the report said. ''This is a major concern for policy makers and service providers.''

Youth Off The Streets founder Father Chris Riley estimated up to 47,000 people under the age of 21 were unaccounted for in the main cities. ''These kids have no stability,'' Father Riley said. ''A young person may be attached to relatives and friends outside of their immediate family, but they can wear out their welcome very quickly. They are as homeless as those on the streets, but just less visible.''

He said people did not realise couch surfing was a form of homelessness. ''Kids may have a bed to sleep in or a couch, but no one makes them go to school, no one makes sure they're fed. If a kid doesn't have a nurturer then they are homeless.''

Cathy Jongens from the Salvation Army Oasis Youth Support Network said it was time people realised how desperate couch surfing is. ''There have been girls who have gone out to clubs to find someone to go home with and have been raped, all just to get a roof over their heads,'' she said.

The Australian Institute of Health and Welfare said 45,000 young people aged between 15 and 24 sought help for homelessness in 2012-13, comprising almost one-fifth of the homeless population.

But Homelessness NSW chief executive Gary Moore said welfare providers also underestimated the actual numbers, as thousands of young people never sought formal assistance. ''Many young people don't realise they are victims of welfare - it's a cultural thing,'' Mr Moore said. ''[And] others who do approach services simply cannot be assisted because there are no spaces.''