EPA Sets PFAS Limits On Public Water Systems

The final rule will require many public water systems to test for and treat certain PFAS in their drinking water supplies.

On April 8, 2024, the U.S. Environmental Protection Agency (“EPA”) announced limits on six per- and poly-fluoroalkyl substances (“PFAS”) in public water systems.   PFAS are a class of synthetic, environmentally persistent chemicals. A range of commercial and industrial applications made them common. EPA has concluded there is no safe level of exposure to PFAS in drinking water. EPA’s final rule (a pre-publication version of which is available here) will set maximum contaminant levels (“MCLs”) under the Safe Drinking Water Act, 42 U.S.C. § 300f et seq., for the following six PFAs at or near the lowest levels current technology can detect:

• For PFOA and PFOS, an MCL of 4 parts per trillion;
• For PFHxS, PFNA, and HFPO-DA, an MCL of 10 parts per trillion; and
• For mixtures containing multiple PFNA, HFPO-DA, PFHxS, and PFBS, an MCL of 1.0 on the Hazard Index approach. (This approach adds the substances’ concentrations divided by each substance’s highest level determined not to have risk of health effects.)

These MCLs will apply to every public water system that serves at least 15 service connections used by year-round residents or regularly serves at least 25 of the same persons for more than six months per year. See 40 CFR § 141.2. EPA estimates the rule will affect 6,700 public water systems serving up to 105 million people.

Surface water systems that serve at least 15 service connections and groundwater systems that serve more than 10,000 people must conduct quarterly PFAS monitoring at sample entry points. Groundwater systems that serve fewer than 10,000 people must sample entry points twice per year during an initial compliance period. 

If a system detects any of the PFAS above a trigger level (i.e., half of the MCL), the system must conduct quarterly monitoring for those PFAS until it can show compliance. A system that detects PFAS above an MCL must engage in treatment.  Conventional water treatment technologies are ineffective at remediating PFAS.  However, EPA has identified several filtration options, including granulated activated carbon filtration, anion exchange filtration, and high-pressure membrane filtration.

Compliance with this rule is likely to prove costly, though funding may be available to help. The rule gives impacted public water systems a two-year “capital improvement extension.” This means they must comply with the MCLs five years after the rule is posted in the Federal Register later this month.

Attorneys at Baird Holm LLP specialize in various subject matter areas including administrative, water, and environmental law. Please do not hesitate to contact us if you have questions about this case or any related matter.