By the time they finish their degrees next year, Ashley Solo and Sarah Davis will have each done 30 weeks of unpaid work.

The students at Sydney's University of Notre Dame are two of more than 20,000 teachers and nurses who fill the nation's school and hospitals on unpaid placements each year, putting a strain on their hip pockets as the cost of living continues its inexorable rise.

"You are just thrown in and [told to] swim... but it is OK," said Ms Davis, who will graduate with a nursing degree next year. She said the placement was an essential part of her degree. "You need the practice in a hospital."

For students earning as little as $300 a week, the yearly 10-week placement they must undertake costs them $3000 a year in income from not being able to work in paying jobs during that time.