The U.S. Environmental Protection Agency (EPA) set its first-ever national, legally enforceable limits on PFAS, also known as “forever chemicals,” in drinking water on Wednesday. 

PFAS, short for per- and polyfluoroalkyl substances, are chemicals widely used in consumer and industrial products to repel oil and resist heat since the 1940s. They break down very slowly and can build up in people, animals, food, and water and may lead to adverse health effects including decreased fertility, development delays, increased risk of cancer, and more, according to the EPA. 

“This new standard will reduce PFAS exposure for approximately 100 million people. It will prevent thousands of deaths and reduce tens of thousands of serious illnesses,” EPA Administrator Michael Regan said at a press conference in Fayetteville, N.C., where residents found out in 2017 that the Cape Fear River, a drinking water source for one million people, was contaminated with PFAS from nearby chemical company facilities. 

“Everyone should be able to turn on their tap and trust that the water that they’re drinking and giving their children is safe,” Regan said. 

The new regulation, which requires public water systems to reduce contamination by 2029, sets limits for five individual PFAS chemicals and for mixtures of at least two of three of these and one more. (There are nearly 15,000 chemicals in the class). Regan said the EPA started with six because it had the best data about them, but added “we’re going to continue until we get all of them.” 

The government estimates roughly 6% to 10% of the country’s 66,000 public drinking water systems subject to this rule may have to take action to meet new standards. Public water systems will have until 2027 to comply with initial monitoring and report drinking water contamination levels to the public. If findings show levels exceed the limits, they must implement solutions to reduce PFAS in the water supply by 2029. 

When the rules come into effect, systems that don’t comply must take action to reduce levels and provide notification to the public of the violation. If the EPA pursues a non-compliant water system, it will rely on its statutory authority and existing enforcement policy (which says it focuses on “return to compliance” rather than simply “addressing” a violation), the agency told TIME in an email. Regan said the EPA would provide technical assistance to water facilities that need it: “We don’t want to leave anyone behind.”

To help, President Joe Biden’s administration is pumping nearly $1 billion in newly available funding to help states, territories, and communities implement PFAS testing and treatment, and to owners of private wells to address contamination. The new funding is part of a $9 billion investment over five years to address PFAS and other contaminant pollution, the administration said. 

Regan said he agreed with “those who say we should be stopping at the source and that’s what we’re doing at the state and federal level.”

“We are holding polluters accountable,” he said, noting settlements with companies nationwide. 

David Andrews, a senior scientist at the Environmental Working Group, tells TIME in an email that the new regulations “are the most health protective drinking water standards that I am aware of anywhere in the world.” 

“For decades, the American people have been exposed to incredibly toxic forever chemicals known as PFAS with no protection from their government. “Those chemicals now contaminate virtually all Americans from birth, in fact before birth,” said Environmental Working Group president and co-founder Ken Cook, who was moved to tears when he described fighting PFAS as his organization’s “life work,” during the press conference. Cook said PFAS evaded U.S. environmental regulation for generations until this administration. 

“Is it enough money to do the job? No, of course not,” Cook  said about the accompanying funding, but added that to get the rest “let’s start with the guy”––meaning Biden—who got the initial money. 

Other speakers honored victims of PFAS contamination. Brenda Mallory, the chair of the Council on Environmental Quality, remembered Amara Strande, 20, who died of cancer in April 2023. Strande was an advocate against PFAS after a chemical plant dumped pollutants, contaminating the water supply of her home in Oakdale, Minnesota and leading to cancer being a far likelier cause of death for children than neighboring communities, Mallory said.   

Emily Donovan, a North Carolina resident and co-founder of non-profit organization Clean Cape Fear⁠, spoke, her voice breaking at times, about how she raised her children on toxic water and lost four friends in recent years to cancer and chronic health problems. 

“I know we can’t change the past, but we can fight for a more just future, and that’s exactly what we’re doing today,” Donovan says. 

Some governments, such as that of Canada and the European Union, have already set limits on PFAS, but these rules haven’t always been effective. A study published by researchers from the University of New South Wales in Australia and one from the University of Oklahoma in the journal Nature Geoscience on April 8 showed that the chemicals exceeded limits set by different countries in surface and groundwaters around the world. 

Researchers found that 31% of water samples in the U.S. exceeded the EPA’s Hazard Index threshold, one of the study’s authors Denis O’Carroll tells TIME in a phone call. O’Carroll, professor of civil and environmental engineering at the University of New South Wales, says the EPA is “quite stringent,” for instance compared to Australia. Despite global violations, he says rules are enforceable. 

“We can certainly treat and measure to those levels––it becomes expensive,” he says. 

“Monitoring is really, really important,” he continues, adding that a local authority can set up a source zone catchment area around a known polluter, and if they find the source water is at risk, put in appropriate systems to clean the water system.  

Andrews points out that cleaning up ground or surface water requires stopping contamination at the source. He says this is possible with restrictions on industrial releases of PFAS, as Michigan has done with success. “In many cases, strict regulation of environmental contamination levels will be difficult due to the large number of PFAS uses and sources,” he adds.

In general, O’Carroll urges caution in a world with a “significant reliance on chemicals,” explaining there’s no “crystal ball” to know the downstream environmental impact. 

“Just because we can use them doesn’t mean we should be using them,” he concludes.