April 11, 2024
On April 10, 2024, the U.S. Environmental Protection Agency (EPA) announced finalization of the first-ever national drinking water standards for per- and polyfluoroalkyl substances (PFAS). This final rule sets enforceable limits for five individual PFAS and mixtures of a combination of up to four PFAS in drinking water.
PFAS are a class of thousands of chemicals that are water-, oil-, and heat-resistant, and have been produced and used since the 1940s in countless consumer and industrial products. The resilient characteristics of these compounds have led to their widespread use in products including cosmetics, water- and stain-resistant clothing, carpets, plastics, firefighting foam, and much more. PFAS exposure has been linked to a number of health concerns, including certain cancers, thyroid issues, liver and heart impacts, and developmental impacts in infants and children. EPA anticipates the new drinking water standards will reduce PFAS exposure from public drinking water for approximately 100 million people.
The new standards apply to public water systems (defined in the Safe Drinking Water Act and its implementing regulations), that are either community water systems (i.e., serve year-round residents) or non-transient, non-community water systems (i.e., are not community water systems and regularly serve at least 25 of the same people over six months per year).
The rule sets the following enforceable standards, called maximum contaminant levels (MCLs), for the listed PFAS:
| Compound | Final MCL |
| Perfluorooctanoic acid (PFOA) | 4.0 parts per trillion (ppt) (also expressed as ng/L) |
| Perfluorooctane sulfonic acid (PFOS) | 4.0 ppt |
| Perfluorohexanesulfonic acid (PFHxS) | 10 ppt |
| Perfluorononanoic acid (PFNA) | 10 ppt |
| Hexafluoropropylene oxide dimer acid (HFPO-DA; commonly known as GenX Chemicals) | 10 ppt |
| Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and perfluorobutanesulfonic acid (PFBS) | 1 (unitless)Hazard Index |
Below are some of the key requirements established in the final rule:
Required Sampling
Initial Monitoring
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- Systems must complete initial monitoring using legally required analytical methods and report the results of that monitoring to EPA or the authorized state by April 26, 2027.
Compliance Monitoring
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- Occurs between April 26, 2027 and April 26, 2029.
- If initial monitoring results are below trigger levels (set at half of the MCLs), then systems may reduce sampling frequency.
- If initial monitoring or compliance monitoring levels are at or above trigger levels, the system must continue sampling frequency.
MCL Compliance
Systems must be in compliance with PFAS MCLs by April 26, 2029. This compliance date, which EPA extended from the date in the proposed rule, accounts for public comments the Agency received on the proposed rule and allows additional time for systems to make capital improvements needed to comply with the MCLs.
Reporting and Recordkeeping
Systems must report sampling results and maintain proper records as described in the regulation. Systems must meet these requirements by April 26, 2027.
Violations
Systems may be assessed monitoring and reporting violations beginning April 26, 2027.
Systems may be assessed MCL violations beginning April 26, 2029.
Systems with PFAS levels above the new standards have multiple treatment technology options to treat their water and bring levels down. These technologies include granular activated carbon, reverse osmosis, and ion exchange. Water systems are also required to provide public notice and include PFAS testing information in Consumer Confidence Reports, pursuant to the new requirements established in the regulation.
EPA has also posted information for consumers on reducing PFAS in drinking water with home filters. This fact sheet provides considerations and tools for proactive consumers who may prefer home filtration, rather than waiting for information or action from their water utility.