An estimated 5.7 million U.S. families live in substandard housing, with one in every three houses in U.S. metropolitan areas plagued by health hazards, according to a study released Thursday.

The National Center for Health Housing, which culled the information from U.S. Census data, said the most common problems are water leaks from the outside (11 percent) and inside (8 percent), roofing problems (6 percent), damaged interior walls (5 percent), and signs of mice (5 percent).

Charlotte, N.C., Anaheim-Santa Ana, Calif., and Atlanta, Ga., rank at the top of the list for having the healthiest housing. The metropolitan areas of San Francisco, Oakland, Los Angeles, and New York ranked as having the least healthy housing.

Source: National Center for Healthy Housing (09/24/2009)