Two annual surveys suggest higher tuition fees are fuelling student debt.
Universities can charge £3,000 a year in fees
Natwest's poll of 3,488 students shows graduates owed £12,363 on average this year, down 6% on 2006 - but expected to rise to £14,841 for new undergraduates.
Another survey of 2,000 for Push.co.uk predicts those who began courses last year will owe nearly £17,500 by the time they graduate, up 24% on 2006.
It says this year's freshers will owe up to £21,500 when they graduate, with some of them struggling financially.
Editor of the Push.co.uk survey Johnny Rich said: "This is the first time we have had genuine figures about what top-up fees have meant."
He claimed the figures meant the government's financial support for students paying variable fees was not working.
"This increase is not just another rise. Some students are facing real financial hardship."
Undergraduates who started their courses in England and Northern Ireland last autumn are the first to be charged top-up fees of £3,000 per year, up from £1,000 under the old system (which had risen to £1,175 with index linking).
They do not pay until after graduation and universities charging top-up fees are required to offer bursaries to help poorer students cope.
The poorest undergraduates should have their course costs met by government grants and university bursaries.
Mr Rich stressed the advantages of having a degree still "vastly outweigh" the costs.
And according to the NatWest survey results, nearly three quarters of sixth-formers agree.
Some 73% said they though university was still worthwhile and that it would improve their future job prospects.
However, 72% said they were already worried about the amount of debt they would be building up.
The head of NatWest student and graduate banking, Mark Worthington, said these factors would clearly influence how students would manage their finances.
"However, thankfully new students seem to be much more aware about the financial realities of university and are trying to prepare themselves accordingly.
More maintenance grants
"Despite the anticipated cost of university continuing to rise, students are taking steps to supplement income and budget their spending and it is encouraging to see that the graduate debt figure is actually down for the first time in six years."
A spokeswoman for the Department for Innovation, Universities and Skills said it was a clear tuition fees were not putting off students as record numbers of people were applying to university.
"A generous package of support is available to students, particularly those from low income families, who can receive maintenance grants of up to £2,700 per annum.
"And from 2008/09 onwards, around two-thirds of new full-time entrants to higher education will be eligible for a full or partial grant - compared to just over half now."
But the National Union of Students said rising debts for students going through the system from 2006 needed to be stemmed if students' choices and welfare were to be protected.