Published: Friday, 8 Feb 2013 | 11:04 AM ET

By: Diana OlickNearly 11 million borrowers are underwater on their mortgages, owing more than their homes are worth, according to CoreLogic, and yet home equity lines of credit are suddenly on the rise again.During the housing boom of the last decade Americans withdrew over $1 trillion in home equity. They did it through cash-out refinances, home equity loans, and home equity lines of credit. The latter allowed them to use their homes like an ATM. They spent the money on cars, televisions, vacations and fancy home upgrades. It was seemingly endless equity, until suddenly that equity was gone.”Home prices are definitely a factor” in the recent rise home equity lines of credit, said Brad Blackwell, an executive with Wells Fargo Home Mortgage. “As they increase, people have more available equity.”