The EPA enacted a historic water-protection rule Wednesday, saying communities across the country must filter out six PFAS chemicals — and in the process, put 10 metro area water systems and 12 others statewide on notice.

That's how many water systems are exceeding the rule now at least in part, according to the Minnesota Department of Health (MDH). Those water systems are in Alexandria, Battle Lake, Brooklyn Park, Cimarron Park, Cloquet, Hastings, Lake Elmo, the Minnesota Veterans Home in Dakota County, Newport, Pease, Pine City, Princeton, Sauk Rapids, South St. Paul, Stillwater, Swanville, Wabasha, Waite Park, Woodbury and three mobile home parks: Austin, Mobile Manor and Roosevelt Court, according to the MDH.

Together, about 309,000 people across the state are drinking water from the 22 systems, MDH reported.

Originally the Health Department indicated 13 systems across the state were above the limits, but updated its count after an analysis of test results. It also initially said Cottage Grove was above the limits, but later clarified the community is in compliance.

"In anticipation of the EPA release, state agencies have been preparing for lower contaminant levels, which puts us in a strong position to continue this work," the MDH and the Minnesota Pollution Control Agency said in a statement.

PFAS chemicals, or per- and polyfluoroalkyl substances, are a class of thousands of chemicals used to make items nonstick, stain resistant, water resistant and even to snuff out fuel fires. But they linger in the environment, build up in people's bodies and have been linked to serious health effects, such as developmental problems, immune issues and some cancers.

On a call with reporters Tuesday, EPA Administrator Michael Regan said the new rule would protect about 100 million people, "prevent thousands of deaths, and reduce tens of thousands of serious illnesses."

Minnesota was one of the first places in the country to reckon with these chemicals. Maplewood-based 3M pioneered PFAS for products such as Scotchgard. But improper disposal of the chemicals from a 3M plant contaminated vast swaths of drinking water in the east metro, a problem first discovered in the early 2000s.

Because of a settlement stemming from that episode, some of the affected water utilities have a pot of money they can use to install filtration or other controls to remove PFAS. Most of them will not — and state officials estimated last year that the costs could reach $1 billion.

As it unveiled its new rule, EPA also announced that it would make $1 billion available to help communities nationwide comply with added costs.

At a media event Wednesday, family members of Amara Strande, a young woman who grew up drinking contaminated water in Oakdale, described how the family was burdened with medical bills, missed work and school and ultimately lost a beloved sister and daughter.

Amara died at the age of 20 almost exactly a year ago, after battling a rare and complex liver cancer for seven years. She was a critical part of the effort to ban PFAS in most products in Minnesota. The law banning the chemicals has been named Amara's Law.

"The cost [of water treatment] is nothing compared to the cost of having a sick family member," said Amara's younger sister, Nora Strande.

Strande's story has become nationally prominent. On a call with reporters Tuesday, Brenda Mallory, the chair of the White House Council on Environmental Quality, gave Amara Strande's hometown as an example of a place where protections were needed to guard human health.

"Today's action is a critical step in striving to ensure that no child or community, no family, no parent experiences the devastation that Oakdale has seen," Mallory said.

EPA originally unveiled its proposal for the first-ever enforceable PFAS limit last year.

Little changed between that draft and final rule unveiled Wednesday, except the agency added some individual limits for three chemicals that had only been regulated as a mixture. For two of the oldest and best-studied PFAS chemicals, PFOS and PFOA, the allowed amounts remain so low they are near the limit of detection.

Regulators also extended the time that public water systems have to comply with the rule. Water providers must test for the chemicals within the next three years, and by 2029, they will have to meet the limits. It's estimated that between 6% and 10% of the 66,000 public water systems in the United States could be in violation of the limits.