Harmful chemicals known as PFAS can be found in everything from children’s clothes to soil to drinking water, and regulating these chemicals has been a goal of public and environmental health researchers for years. On March 14, 2023, the U.S. Environmental Protection Agency proposed what would be the first set of federal guidelines regulating levels of PFAS in drinking water. The guidelines will be open to public comment for 60 days before being finalized.

Joe Charbonnet is an environmental engineer at Iowa State University who develops techniques to remove contaminants like PFAS from water. He explains what the proposed guidelines would require, how water utilities could meet these requirements and how much it might cost to get these so-called forever chemicals out of U.S. drinking water.

1. What do the new guidelines say?

PFAS are associated with a variety of health issues and have been a focus of environmental and public health researchers. There are thousands of members of this class of chemicals, and this proposed regulation would set the allowable limits in drinking water for six of them.

Two of the six chemicals—PFOA and PFOS—are no longer produced in large quantities, but they remain common in the environment because they were so widely used and break down extremely slowly. The new guidelines would allow for no more than four parts per trillion of PFOA or PFOS in drinking water.

Four other PFAS—GenX, PFBS, PFNA and PFHxS—would be regulated as well, although with higher limits. These chemicals are common replacements for PFOA and PFOS and are their close chemical cousins. Because of their similarity, they cause harm to human and environmental health in much the same way as legacy PFAS.

A few states have already established their own limits on levels of PFAS in drinking water, but these new guidelines, if enacted, would be the first legally enforceable federal limits and would affect the entire U.S.

Chemicals used to create water-repellent fabrics and nonstick pans often contain PFAS and leak those chemicals into the environment. Brocken Inaglory/Wikimedia Commons, CC BY-SA

2. How many utilities will need to make changes?

PFAS are harmful even at extremely low levels, and the proposed limits reflect that fact. The allowable concentrations would be comparable to a few grains of salt in an Olympic-size swimming pool. Hundreds of utilities all across the U.S. have levels of PFAS above the proposed limits in their water supplies and would need to make changes to meet these standards.

While many areas have been tested for PFAS in the past, many systems have not, so health officials don’t know precisely how many water systems would be affected. A recent study used existing data to estimate that about 40% of municipal drinking water supplies may exceed the proposed concentration limits.

3. What can utilities do to meet the guidelines?

There are two major technologies that most utilities consider for removing PFAS from drinking water: activated carbon or ion exchange systems.

Water treatment systems can use activated carbon or ion exchange to remove PFAS from drinking water. Paola Giannoni/E+ via Getty Images

Activated carbon is a charcoal-like substance that PFAS stick to quite well and can be used to remove PFAS from water. In 2006, the town of Oakdale, Minnesota, added an activated carbon treatment step to its water system. Not only did this additional water treatment bring PFAS levels down substantially, there were significant improvements in birth weight and the number of full-term pregnancies in that community after the change.

Ion exchange systems work by flowing water over charged particles that can remove PFAS. Ion exchange systems are typically even better at lowering PFAS concentrations than activated carbon systems, but they are also more expensive.

Another option available to some cities is simply finding alternative water sources that are less contaminated. While this is a wonderful, low-cost means of lowering contamination, it points to a major disparity in environmental justice; more rural and less well-resourced utilities are unlikely to have this option.

4. Is such a major transition feasible?

By law, the EPA must consider not just human health but also the feasibility of treatment and the potential financial cost when setting maximum contaminant levels in drinking water. While the proposed limits are certainly attainable for many water utilities, the costs will be high.

The federal government has made available billions of dollars in funding for treating water. But some estimates put the total cost of meeting the proposed regulations for the entire country at around US$400 billion—much more than the available funding. Some municipalities may seek financial help for treatment from nearby polluters, while others may raise water rates to cover the costs.

5. What happens next?

The EPA has set a 60-day period for public comment on the proposed regulations, after which it can finalize the guidelines. But many experts expect the EPA to face a number of legal challenges. Time will tell what the final version of the regulations may look like.

This regulation is intended to keep the U.S. in the enviable position of having some of the highest-quality drinking water in the world. As researchers and health officials learn more about new chemical threats, it is important to ensure that every resident has access to clean and affordable tap water.

While these six PFAS certainly pose threats to health that merit regulation, there are thousands of PFAS that likely have very similar impacts on human health. Rather than playing chemical whack-a-mole by regulating one PFAS at a time, there is a growing consensus among researchers and public health officials that PFAS should be regulated as a class of chemicals.

Republished with permission from The Conversation, by Joe Charbonnet, Assistant Professor of Environmental Engineering, Iowa State University