As of October 2026 there is no federal limit for PFAS in biosolids. EPA’s January 2025 draft risk assessment for PFOA and PFOS in sewage sludge is still a draft, and in July 2026 EPA followed it with draft guidance that is voluntary and non-binding. The enforceable rules are being written by the states, and they range from tiered concentration limits to complete bans on land application. Composting does not destroy PFAS, so a compost project does not solve a PFAS problem in the solids.

Key takeaways

• 40 CFR Part 503 sets limits for metals and pathogens, not PFAS. EPA’s current documents on PFAS in biosolids are a draft risk assessment and a draft, voluntary guidance memo.
• EPA recommends that states monitor biosolids for PFAS, identify likely industrial discharges and use industrial pretreatment where appropriate.
• State rules are what bind a utility today. Maine bans land application of sludge and sludge-derived compost. Michigan prohibits land application above 100 parts per billion and restricts it above 20.
• Composting, digestion and other conventional solids treatment do not destroy PFAS. What is in the cake will be in the product.
• Source control is the tool with a track record. Test the solids, find the industrial contributors, and decide on outlets after you know your numbers.

What PFAS are and how they reach biosolids

PFAS (per- and polyfluoroalkyl substances) are a large class of synthetic chemicals. PFOA and PFOS are the two that regulators have studied most. EPA’s draft guidance memo says they persist in the environment for long periods and have been linked to a variety of significant adverse human health effects. It adds that not all sewage sludge has detectable or elevated levels.

Treatment plants do not make PFAS. They receive it. Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) explains on its PFAS in biosolids page that landfill leachate sent to a treatment plant can be a source, and that studies have found PFAS in sewage sludge even at plants that receive only residential and commercial wastewater. Industrial dischargers are the source that can push concentrations far above that background.

The federal position as of October 2026

Part 503 has no PFAS limits

The federal biosolids rule, 40 CFR Part 503, sets limits for metals, pathogens and vector attraction. It contains no PFAS limit. EPA’s draft guidance states that it does not supersede existing federal law or regulations, or any state, Tribal or local requirement.

The January 2025 draft risk assessment

On January 14, 2025, EPA released the Draft Sewage Sludge Risk Assessment for PFOA and PFOS (Docket EPA-HQ-OW-2024-0504). The comment period was extended twice and closed on August 14, 2025. EPA’s page, last updated in July 2026, still describes the document as a draft.

The draft addresses land application, surface disposal and incineration. EPA’s question and answer page says the assessment is not meant to predict true risks at any specific site, that it models a range of land application scenarios, some of which may not be common practice, and that the people of concern are those living on or near impacted sites, such as farm families and their neighbors, or those who rely primarily on their products. The same page recommends EPA Method 1633 for measuring PFAS in sewage sludge and points to EPA’s December 2022 permitting memo, which recommends pretreatment best management practices to reduce PFAS sources along with quarterly monitoring of influent, effluent and sewage sludge.

The July 2026 draft guidance

On July 1, 2026, EPA released a memorandum titled Draft Guidance for Reducing Risk from PFOA and PFOS in Biosolids (Docket EPA-HQ-OW-2026-2509). EPA extended the public comment period once, from September 4, and scheduled it to close on October 5, 2026. Check the EPA page for what the agency does next.

In the memo, EPA says it has determined that the draft risk assessment had serious flaws: no national survey of PFOA and PFOS in sewage sludge, a focus on higher-risk hypothetical scenarios that do not reflect the majority of land application, and the use of 1 part per billion as a modeled starting concentration. EPA writes that 1 part per billion was not intended to be interpreted as a safe level in all circumstances. The memo also restates EPA’s support for land application, noting that nearly 60 percent of sewage sludge is land applied and about 20 percent is sold to the public.

Its recommendations are voluntary. In summary:

• Bulk land appliers: avoid application near fishable waters, drinking water reservoirs and areas with higher groundwater risk; avoid areas where children under five have access; prefer lower-risk crops such as grain, fiber crops or corn for ethanol.
• The general public: research the supplier of any biosolids product; avoid using it where children have access to the soil; avoid garden beds for leafy greens and root vegetables and areas where laying hens forage.
• Treatment plants: identify sources, prevent pollution and monitor; consider a composite liner for surface disposal units; consider performance testing of incinerators, because EPA says current operating conditions may not be effective for treating PFOA, PFOS and other PFAS.

EPA’s PFAS in sewage sludge page adds that the agency is planning the next National Sewage Sludge Survey to obtain current national data on PFAS concentrations, and that in the meantime it recommends that states monitor biosolids for PFAS contamination, identify likely industrial discharges of PFAS and implement industrial pretreatment requirements where appropriate.

For materials that must be disposed of, EPA’s Interim Guidance on the Destruction and Disposal of PFAS, in its April 2026 version, covers thermal destruction, landfills and underground injection.

What states are doing

EPA’s draft guidance groups state actions into three kinds: source reduction and pretreatment programs, monitoring requirements, and prohibitions on land application. Two states verified on their own pages for this guide show the two ends of that range.

	Maine	Michigan
Approach	Statutory ban	Tiered interim strategy run by the state agency
What is restricted	Applying sludge, or compost containing sludge, to any land in the state, and selling or distributing such compost	Land application above set PFOS and PFOA concentrations
Thresholds	None. The ban applies regardless of concentration	Below 20 ppb: notify the landowner or farmer of results. 20 to 100 ppb: also reduce the application rate to 1.5 dry tons per acre or submit an alternative, sample the discharge and implement a source reduction plan. Above 100 ppb: land application prohibited
Since	Public Law 2021, Chapter 641, effective August 8, 2022	2021, modified in 2022 and 2024
Where solids go	Landfill disposal remains allowed	Land application continues for most facilities

Maine

The Maine DEP says the legislature was the first in the nation to ban the land application of sludge and sludge-derived products. The statute, 38 M.R.S. section 1306(7), prohibits applying or spreading sludge, compost containing sludge or septage, and similar products on any land in the state, and prohibits selling or distributing such compost. Disposal at a solid waste landfill is still allowed. For a utility, that means composting is not an outlet in Maine. EPA’s draft guidance reports that the ban has led to significant issues and cost increases for Maine utilities, because landfill capacity is limited and the state has no sewage sludge incinerators.

Michigan

Michigan kept land application and went after the sources. EGLE requires every facility that land applies Class A or Class B biosolids to sample the finished product at least once a year, and quarterly for biosolids designated Exceptional Quality. EGLE reports that the statewide mean PFOS concentration fell from 184 ppb in 2018 (a figure that included industrially impacted plants) to 8 ppb in 2024, with a 2024 median of 5 ppb, and that most of the 173 facilities reporting in 2024 were below 20 ppb.

Other states

EPA’s draft guidance, not the states’ own pages, is the source for the rest of the picture. It says Wisconsin, Minnesota, Colorado, Maryland and Virginia have adopted tiered approaches similar to Michigan’s, that Virginia recently approved legislation using a 50 ppb threshold, that Washington, Oregon and Florida have enacted monitoring requirements, and that Connecticut banned the sale and use of sewage sludge containing PFAS in 2024. Verify any of these with the state agency before relying on them.

Composting does not destroy PFAS

This point needs to be stated without qualification. Composting is a biological process that stabilizes organic matter and reduces pathogens. It is not a PFAS treatment. PFAS that enter a compost pile in the biosolids leave it in the compost.

• Peer-reviewed work supports this. A 2026 study in ACS Omega on PFAS release from biosolid-derived compost measured PFAS in finished compost made from biosolids and notes that PFAS precursors in biosolids can be biotransformed into terminal PFAS.
• Regulators treat it this way. Maine’s statute covers compost containing sludge in the same sentence as sludge itself, and Michigan’s sampling requirement applies to the finished biosolids product.
• Adding a bulking agent changes the concentration by adding mass. It does not remove anything, and the total PFAS applied to land with the product is unchanged.

The same caution applies to equipment. No composting system, including Sustainable Generation’s covered aerated static pile technology with the GORE® Cover, removes or destroys PFAS, and SG makes no such claim. A covered ASP system is a way to meet pathogen and stabilization requirements and to manage odor and water at the pile. Whether the product is acceptable for land depends on what is in the solids.

What this means for each outlet

Outlet	PFAS consideration as of October 2026
Class B land application	Governed by state rules. Tiered states cap or prohibit application above set concentrations. EPA’s draft guidance suggests site and crop choices that lower exposure
Class A compost or other distributed products	PFAS carry through to the product. EPA’s draft guidance tells the public to research the supplier and avoid use where children play or on leafy greens and root vegetables. Banned in Maine
Landfill	Still allowed under Maine’s ban. PFAS can move into leachate, which often returns to a treatment plant
Surface disposal (monofill)	Regulated under Part 503. EPA’s draft guidance suggests considering a composite liner
Incineration	EPA says current sewage sludge incinerator conditions may not be effective for treating PFAS and suggests performance testing

A step sequence for utilities

1. Sample the solids. Use EPA Method 1633 and a lab experienced with biosolids. EPA’s question and answer page cites the agency’s December 2022 memo, which recommends quarterly monitoring of influent, effluent and sludge.
2. Compare results with your state’s current rule and with the tiers other states use, since thresholds have moved downward over time.
3. Find the sources. Review industrial users, landfill leachate and hauled waste. Michigan’s results show how much industrial pretreatment can lower concentrations.
4. Decide on outlets after the numbers are in. Low concentrations with effective source control support continued beneficial use, including compost. High concentrations call for source reduction first and a disposal outlet in the interim.
5. Tell your customers what you know. If you distribute compost, publish your PFAS results alongside the other compost quality metrics.
6. Ask about funding. EPA’s draft guidance points to the Clean Water State Revolving Fund and the WIFIA program for PFAS-related work in wastewater.

For utilities whose solids are suitable for composting, the process itself is covered in our biosolids composting guide and on SG’s biosolids composting page. See also our lists of biosolids composting technologies, compost feedstocks and uses of compost in agriculture.

FAQ

Is there a federal limit for PFAS in biosolids?

No. As of October 2026, 40 CFR Part 503 has no PFAS limit. EPA has published a draft risk assessment for PFOA and PFOS (January 2025) and a draft, voluntary guidance memo (July 2026), with a public comment period on the guidance that was scheduled to close on October 5, 2026. Neither document is a regulation. Enforceable limits, where they exist, come from state law or state permits.

Does composting remove PFAS from biosolids?

No. Composting does not destroy PFAS. It reduces pathogens and stabilizes organic matter, but PFAS in the incoming solids remain in the finished compost. Blending with a bulking agent lowers the concentration by adding mass without removing any PFAS. Some precursor compounds can also transform into terminal PFAS during biological treatment.

What does the 1 part per billion figure mean?

EPA’s 2025 draft risk assessment used 1 part per billion of PFOA or PFOS as the starting concentration in its models. In its July 2026 draft guidance, EPA says that figure was not intended to be read as a safe level in all circumstances and that the modeled scenarios were higher-risk hypothetical cases. It is not a federal limit.

Which states ban land application of biosolids?

Maine banned land application of sludge and sludge-derived compost through Public Law 2021, Chapter 641, effective August 8, 2022. EPA’s draft guidance also describes a 2024 Connecticut law banning the sale and use of sewage sludge containing PFAS. Most other states that have acted use monitoring requirements or tiered concentration limits. Check your own state agency for current rules.

Should a utility stop a composting project because of PFAS?

Not automatically. Test first. Michigan’s data show most facilities there below its lowest tier, and EPA continues to support beneficial use. If results are low and sources are controlled, composting remains a sound way to reach Class A. If results are high, composting will not fix that, and source reduction comes first.

Next step

If your sampling supports beneficial use and you are weighing compost as the outlet, continue with the biosolids composting guide below, then see how SG’s covered ASP process works. Bring your PFAS results to any vendor conversation at the start.

Related guides

• Biosolids composting: a guide for wastewater utilities
• Composting system buyer’s guide for wastewater utilities
• Composting digestate: a guide for anaerobic digester operators
• How to run a composting pilot
• How to fund a compost facility

← All commercial composting guides

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