Tests show that the filters, distributed to homes by Michigan state agencies, reduce the level of lead in drinking water to less than 1 part per billion, well below the EPA's action level of 15 parts per billion.
"These findings reaffirm the effectiveness of filters at removing or reducing lead. This is an important step forward for providing a stable water system for the city of Flint," said Tom Burke, EPA Science Advisor and Deputy Assistant Administrator for EPA's Office of Research and Development.
The EPA reported that the water, if properly filtered, is safe for all to drink, including those more susceptible to the effects of lead poisoning such as pregnant and nursing women, and children.
"Residents can be confident that they can use filtered water and protect their developing fetus or young child from lead," US Department of Health and Human Services Assistant Secretary Dr. Nicole Lurie said in a statement.
However, not all homes in the city can be fitted with filters, according to Flint mayor Karen Weaver, and bottled water is still required at many locations.
"This is not the ultimate solution," she stated. "We still need new infrastructure, replacing the lead-tainted pipes in the city remains my top priority."
Corrosive Flint River water caused lead to leach from aging pipes into the water they were carrying, a condition that cannot be reversed by simply switching the water source back. A full replacement of almost the entire drinking water infrastructure is required in the city of 100,000.