EPA's Draft PFAS Biosolids Guidance: What It Says, the 1 ppb Reversal, and the October 5 Comment Deadline

Much of the PFAS talk at WEFTEC this week is about drinking water, but there is a second PFAS problem on the program: the solids. Every wastewater plant makes sewage sludge, most of it ends up on land, and PFAS that enter the plant, PFOS especially, accumulate in it. In July the EPA put out draft guidance on what plants, farmers and gardeners should do about that, and in the same document said the 1 ppb figure from its own 2025 risk assessment was a modeling starting point, not a safe level. Comments close on October 5.

What EPA said in 2025, and what it says now

On January 14, 2025, the EPA released a Draft Sewage Sludge Risk Assessment for PFOA and PFOS. Its central finding was that land-applying sludge containing 1 ppb of PFOA or PFOS could exceed EPA's acceptable risk thresholds in some modeled scenarios, and that drinking groundwater near an unlined or clay-lined surface disposal site could exceed them at 1 ppb PFOA or 4 to 5 ppb PFOS. The fact sheet that came with it said the calculations were "not conservative estimates," because 1 ppb is "on the low end of measured U.S. sewage sludge concentrations" and the model left out combined PFOA and PFOS exposure, other sources, and precursor chemicals that transform into PFOA and PFOS.

The June 29, 2026 draft guidance memo, signed by Assistant Administrator Jessica L. Kramer, reassesses the same document. It says EPA determined the draft risk assessment "exhibited a number of serious flaws," and lists three:

Neither document is final. The 2025 risk assessment is still a draft, and the 2026 guidance is a draft that, if finalized, would offer voluntary recommendations. It states that the guidance does not supersede federal law, "nor does it supersede any state, Tribal, or local requirements." For a utility, that means the state rules in the next section are what actually bind today.

Where the sludge goes

The guidance cites the 2024 Biosolids Annual Reports submitted to EPA. About 60% of all sewage sludge is land applied, roughly 2.3 million dry metric tons a year, split like this:

EPA's own arithmetic puts that on less than 1% of US farmland: even at one dry metric ton per acre, 2.3 million tons covers 2.3 million acres, against 237 million acres treated with chemical fertilizers, lime or other soil conditioners. The median application rate is closer to 3 tons per acre. The 20% sold to the public is the part the guidance singles out for households, because it may be applied to home gardens, parks, schools and playgrounds.

What states already require

The federal document is voluntary. Several states are not. The guidance itself lists them as examples, while noting they "should not be interpreted as the EPA's endorsement":

• Michigan uses PFOS as an indicator and a tiered system built in 2018. Seven plants with industrial sources cut PFOS in their sludge by up to 99% through industrial pretreatment. By 2026, land application is prohibited above 100 ppb PFOS, down from 150 ppb in 2021. Michigan notes the tiers were not derived from health endpoints; they were built to find the biggest industrial sources.
• Virginia passed Senate Bill 386 in 2026. It prohibits land application if PFOA or PFOS exceeds 50 ppb, and two years after the program starts, if PFOA and PFOS combined exceed 50 ppb.
• Wisconsin, Minnesota, Colorado and Maryland use tiered frameworks with industrial pretreatment, some with lower tiers than Michigan's.
• Washington, Oregon and Florida have passed laws requiring PFAS monitoring of sludge.
• Maine banned all land application of sewage sludge in 2022, regardless of PFAS level. About 40% of its sludge had been land applied, and the guidance says the ban "has led to significant issues and cost increases for utilities in Maine where landfill capacity is limited and there are no in-state sewage sludge incinerators."
• Connecticut banned the sale and use of sludge containing PFAS in 2024. About 93% of its sludge was already incinerated, and EPA says the ban "was not anticipated to cause widespread disruptions."

Why PFOA and PFOS end up in sludge, and why treatment doesn't touch them

EPA's 2025 fact sheet says it directly: "Traditional wastewater treatment technology does not remove or destroy PFOA or PFOS, and these chemicals typically accumulate in the sewage sludge." Here is the chemistry behind that sentence.

They are surfactants. PFOS (C₈F₁₇SO₃⁻) and PFOA (C₇F₁₅COO⁻) each have a fully fluorinated carbon tail and a charged head. The tail repels water and oil alike, which is why these molecules were so useful in firefighting foam, stain repellents and water-resistant coatings. In a treatment plant, that structure drives them to interfaces and onto solids. PFOS, with its longer tail and sulfonate head, sorbs strongly and largely stays with the sludge; PFOA sorbs less, and more of it leaves with the treated effluent.

The carbon-fluorine bond doesn't break under plant conditions. Sludge treatment is designed to stabilize organic matter and reduce pathogens, not to break C–F bonds:

This is the same reason the drinking-water side of PFAS treatment relies on carbon, ion exchange and reverse osmosis rather than chemical oxidation. We lay out that treatment train in our PFAS removal guide. Moving PFAS from water onto a solid concentrates it but doesn't destroy it, and in a wastewater plant, the solid is the sludge.

"Fighting PFAS With Fire": destruction at WEFTEC

If treatment can't break PFAS and land application is being restricted, the remaining options are to contain it (landfill or lined surface disposal) or destroy it. Destruction is the subject of Wednesday's WEFTEC session "Fighting PFAS With Fire: Advanced Thermal Conversion for Biosolids Management."

One of the technologies in that session is supercritical water oxidation. Above its critical point, about 374 °C and 22.1 MPa, water stops behaving as a separate liquid and gas and becomes a single dense fluid in which oxygen and organic material mix completely. The company 374Water builds its process around that condition. In a September 22 release, it said it will present data at WEFTEC showing "greater than 99.4% destruction and removal efficiency" for every PFAS compound detected in a commercial-scale biosolids demonstration. Those are the company's figures, to be presented on Wednesday, September 30 at 2:30 p.m. CT; they are not an EPA finding.

EPA's own framework for thermal destruction is its Interim Guidance on the Destruction and Disposal of PFAS and Materials Containing PFAS, updated in an April 2026 version. The biosolids guidance points incinerator operators to it and suggests performance testing, including the OTM-45 method for PFAS emissions and the newer OTM-50 for more volatile products of incomplete combustion.

What the draft guidance recommends

For wastewater plants

• Find the sources. Monitor sludge for PFAS; the mix of compounds found can point to which dischargers are contributing.
• Surface disposal: consider a composite liner on sludge-only landfills (monofills), with leachate handled per EPA's destruction and disposal guidance.
• Incineration: consider performance testing to measure releases from incomplete combustion.
• Funding: the Clean Water State Revolving Fund emerging-contaminants program and WIFIA.

For farmers and land appliers

• Avoid land application near fishable waters, drinking-water lakes or reservoirs, and areas with higher groundwater risk.
• Avoid areas where children under 5 have or may have access.
• Prefer lower-exposure crops such as grain, fiber, and corn for ethanol.

For the public

The guidance says current data do not show "widespread impacts to the food supply from biosolids containing PFOA and PFOS at the national level." It notes that the FDA's Total Diet Study rarely finds PFOA or PFOS in grocery foods, except fish: about 40% of sampled grocery fish had detectable PFOS, with a maximum of 610 ppt in catfish. For people using bagged biosolid products, it suggests researching the supplier, keeping them away from places children play, and not using them on beds growing leafy greens or root vegetables, or where egg-laying hens forage.

How to comment before October 5

Comments go to docket EPA-HQ-OW-2026-2509 on regulations.gov. The original deadline was September 4; EPA extended it to October 5, 2026. EPA held listening sessions on August 12 and 18, and the recordings are in the docket. EPA says it may use the comments to inform future actions.

For utilities and anyone who manages sludge, the comments most likely to matter are specific ones: measured PFOA and PFOS concentrations, what source-control programs actually achieved, what disposal costs did when options closed (Maine is the case study EPA itself cites), and whether the proposed practices are workable at your site.