More than 800,000 U.S. households left or chose to never sign up for banking accounts in the past two years, making them part of a growing group of Americans who exist without savings and checking accounts, the Federal Deposit Insurance Corp. said Wednesday.

The FDIC released its "2011 National Survey of Unbanked and Underbanked Households", reporting that one in four U.S. households, or approximately 28.3%, are either unbanked or underbanked.

About 821,000 U.S. households joined the ranks of the unbanked since the last survey was conducted back in 2009. 

Overall, 8.2% of all U.S. households –  or approximately 10 million homes  –  have no banking accounts at all.

And of those who canceled or refused to start accounts, half claim they do not have enough money for an account or simply do not need one. 

The survey, which the FDIC and the Census Bureau conducts every two years, shows three in every ten households exist with an established savings account. 

"The results of the 2011 National Survey of Unbanked and Underbanked Households indicate that insured financial institutions have an important chance to grow their customer base by expanding opportunities that bring unbanked and underbanked individuals into mainstream banking" said FDIC acting chairman Martin J. Gruenberg.

Of the households surveyed, a quarter have had to rely on at least one alternative financial service such as non-bank check cashing or payday lenders in the past 12 months.

One in ten households have used two or more alternative financial products, according to the survey.