A decade after the Great Recession, Americans' level of debt is on the rise again. That's true even of adults so young they can't legally drink.

Those who are part of Generation Z (aged 16-20) already have an average debt of $4,343, according to a new survey by Charles Schwab of 2,000 young adults. Meanwhile, young millennials (aged 21-25) have a whopping $11,663 on average in total debt so far, including student loans and credit card debt.

"It's kind of a debt culture," Carrie Schwab-Pomerantz, a financial adviser, board chair and president of the Charles Schwab Foundation, tells CNBC Make It.

America's young adults don't have robust savings, either. Almost half surveyed had less than $250 saved.

"Kids of the Great Recession are now on the cusp of financial independence and making decisions that will have a lasting impact on their long-term ability to build wealth," Schwab-Pomerantz says. So it's concerning that there's a lot of misunderstanding about debt. For example, one in five young adults surveyed believe home mortgages are "bad debt," and almost 40 percent call student loans "bad debt." Meanwhile, 27 percent labeled revolving debit, such as credit card debt, "good debt."

Experts consider mortgages and student loans to be "good debt," because they are typically low cost and may have tax advantages, and credit card debt to be "bad" because it has much higher interest rates.

It can be confusing, Schwab-Pomerantz says, but there's an easy way to think about it. "Good debt is bad debt when you're drowning in it," she says. "If you have too much of anything, even if it seems good, it's bad when it comes to debt."

When it comes to student loans, she suggests not taking out more, total, then you believe you will make with your first year's salary. So if you think you're going to earn $50,000, you shouldn't have more than $50,000 in student loans.

Schwab-Pomerantz recommends keeping your total amount of debt ⎼ including mortgage, credit card, car- and other loans ⎼ to less than 36 percent of your total gross income.

"I get that people want to stretch, but you don't want to drown in debt," she says.

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