Biosolids are treated sewage sludge meeting EPA Part 503 standards for land application. The source is typically central domestic wastewater systems serving denser urban and industrial areas. New York City alone generates approximately 1,400 tons of biosolids per day — over 500,000 tons per year — with about 31% beneficially used for composting or mine reclamation. In 1987, the U.S. Congress passed the Water Quality Act, directing the EPA to establish a program to reduce environmental risks from sewage sludge and maximize its beneficial reuse. Today, roughly 2.4 million dry metric tons of biosolids are land-applied to U.S. farmland annually as a nutrient source and soil amendment.

The problem:  In 1987, the industry was not yet aware of the risks posed by per- and polyfluoroalkyl substances (PFAS) — a group of synthetic chemicals used in non-stick cookware, waterproof fabrics, and firefighting foams. As PFAS use expanded from industry into consumer products, and as supply chains shifted to developing countries, PFAS levels in our waste streams have risen sharply. The average U.S. resident now gets 60–80% of their PFAS exposure through diet and food, with consumer products (~10%), airborne exposure (5–15%), and drinking water (up to 20%) accounting for the rest.

Why PFAS Concentrates in Biosolids

Wastewater treatment plants do not destroy PFAS.  PFAS can be both hydrophilic, i.e., mix easily with water and move through soil quickly; while others are hydrophobic and tend to bound with solids over mixing with water.  Mass balance studies consistently show that 80–98% of total PFAS mass leaves treatment plants in the liquid effluent (hydrophilic), with only 2–13% partitioning into the solid biosolids fraction (hydrophobic).  

However, because many PFAS compounds are hydrophobic — they repel water — they tend to bind to solids, i.e., the biosolids. When water is removed to create biosolids for land application, the PFAS remains behind in a concentrated form. Applying these solids to farmland transfers that contamination to soil, crops, livestock, and — critically for rural communities — groundwater and the associated private wells and headwater streams in the community.  This statement is more true NOW then the first time I heard it in 1980s, i.e., We All Live Downstream. 

Typical PFAS Concentrations in Biosolids

Concentrations vary widely depending on wastewater sources (domestic vs. industrial inputs such as landfills, metal finishing, or paper mills), treatment processes, and which PFAS compounds are measured. EPA Method 1633 targets approximately 40 compounds, but many precursors are not yet routinely captured.

• PFOS is typically the most abundant terminal PFAS in U.S. biosolids, ranging from 0.4 to 990 ppb, with most municipal samples in the 5–50 ppb range. North Carolina reported 3–256 ppb; Washington State found most samples below 60 ppb PFOS and 20 ppb PFOA. Michigan averages have declined to ~8 ppb PFOS and ~5 ppb PFOA following source control on industrial dischargers.
  
  
• PFOA is generally lower, often 1–20 ppb in municipal biosolids.
  
  
• Total targeted PFAS commonly fall in the tens to low hundreds of ng/g. A Quebec study of 80 PFAS found biosolids ranging from 12 to 1,310 µg/kg, with polyfluoroalkyl phosphoric acid diesters (diPAPs) frequently dominant.
  
  
• Precursor compounds can transform into terminal PFAS (such as PFOA or PFOS) during treatment or after land application. Anaerobic digestion and composting can actually increase measured PFAS levels through this transformation. Incineration is more effective at reducing PFAS, but is not a complete solution — the most durable fix is removing these chemicals from the supply chain entirely.

Facilities that use PFAS in manufacturing discharge them into local wastewater systems. Plants receiving large industrial loads tend to have higher concentrations of longer-chain PFAS. Areas served primarily by domestic wastewater tend to show lower levels and shorter-chain compounds — a reflection of PFAS in everyday consumer products. A comprehensive management strategy must include:

1. Eliminating PFAS from manufacturing processes and supply chains.
   
   
2. Community education to reduce use of high-PFAS consumer products.
   
   
3. Better industrial pretreatment and waste segregation.
   
   
4. Enhanced removal or destruction of PFAS at treatment facilities.
   
   
5. Tools and practices to manage PFAS already present in agricultural soils.

Application on Farm Fields and Environmental Fate

Biosolids are applied to millions of U.S. farmland acres annually. Estimates of potentially affected cropland range from several million to tens of millions of acres, depending on assumptions about Class A vs. Class B material and historical application records.

Once applied to soil:

• Long-chain PFAS (especially PFOS) tend to remain in surface soil (0–30 cm) and persist for decades; repeated applications cause accumulation.
  
  
• Short-chain PFAS are more mobile and can leach toward groundwater or move via runoff and tile drainage.
  
  
• Studies of working farms in Pennsylvania, Minnesota, and the Northeast consistently find higher PFAS detections in biosolids-amended soils versus control fields; PFOS levels have reached tens to hundreds of ppb in some cases.
  
  
• Crop uptake is compound- and plant-part specific. Short-chain PFAS are taken up more readily; detection is more common in forage and stover (leaves, cobs and stalks), than in grain. Livestock grazing amended fields can accumulate PFOS in milk and meat.  For some, we may be a bit too late.  For example, Maine dairy farms have documented extreme levels of PFOS and other per- and polyfluoroalkyl substances (PFAS) in raw cow's milk.

Leaching studies show that even a single biosolids application can produce leachate exceeding groundwater screening values at certain sites. Biochar amendments have shown some promise in reducing leaching of certain compounds in experimental settings.

Test Your Rural Drinking Water & Irrigation Sources for PFAS

If your property has received biosolids applications — or is near farmland that has — your private well or irrigation water source may already be affected. Don’t wait for a regulatory threshold to be set. Get data now.

• Deluxe Well Water Test Kit with PFAS, VOCs, Pesticides & Foaming Agents (107 Analytes) — comprehensive screening for private wells on or near agricultural land.
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Risks and Regulatory Status

In January 2025, the EPA released a draft Sewage Sludge Risk Assessment for PFOA and PFOS, modeling 40 years of application at 10 dry metric tons per hectare of biosolids containing 1 ppb of either compound. It found that certain high-exposure pathways — farm families relying on homegrown milk, meat, crops, fish, or well water — could exceed EPA cancer and non-cancer risk thresholds, sometimes by wide margins. The EPA noted the assessment did not indicate widespread contamination of the general U.S. food supply, and the methodology was criticized for relying on hypothetical high-risk scenarios without first conducting a national occurrence survey.

In July 2026, the EPA issued draft voluntary guidance rather than finalizing binding regulations. It recommends avoiding biosolids application near waterways or areas frequented by young children, favoring lower-uptake crops (grains, fiber crops, ethanol corn), and pursuing source reduction. As of this writing, there are no federal numeric limits or mandatory monitoring requirements for PFAS in biosolids.

States have moved faster, creating a regulatory patchwork:

• Maine and Connecticut have effectively banned land application of municipal biosolids.
  
  
• Michigan, Virginia, Maryland, and others require monitoring and are implementing concentration thresholds (typically 20–100 ppb for PFOA/PFOS combinations) that trigger restrictions or bans.
  
  
• Many additional states require testing and reporting without yet setting numeric limits.

Source control through industrial pretreatment remains the most effective near-term tool. Alternative disposal options: landfill, incineration, and emerging technologies, such as: pyrolysis and supercritical water oxidation, show promise for PFAS destruction but are not yet deployed at scale.

Research is ongoing on precursor transformation, long-term field fate, crop-specific uptake, and destruction technologies. Farmers concerned about a specific site should request recent biosolids test results from the supplier (using EPA Method 1633) and consider independent soil and water testing, particularly if there is a history of industrial wastewater inputs or repeated biosolids applications.

Urban watershed organizations have been quick to highlight the downstream impacts of agricultural runoff and headwater development, but far slower to acknowledge what urbanization has done to rural America. The biosolids issue makes that imbalance hard to ignore. The PFAS contaminating rural soils and private wells did not originate on the farm. It came from urban and industrial waste streams, transported into the countryside under the banner of beneficial reuse. The impacts of our cities and industries are not just downstream — they are in the soil, the crops, and the drinking water of the communities that feed this country.

Know What's in Your Drinking Water

PFAS contamination doesn't stop at the farm fence — it can reach your tap. Our Drinking Water Guide for Well Water & City Water by Brian Oram gives you the data-backed framework to understand your water quality risks, what to test for, and how to protect your household. Whether you're on a private well or a municipal system, this booklet cuts through the confusion with actionable guidance.

→ Order the 2024 Drinking Water Guide Booklet

Recommended Reading

PFAS Forever Chemicals: Breaking the Man-Made PFAS Cycle

How to Manage the Issue of "Forever Chemicals," "PFOA," and "PFAS" in Your Life

Estimating Safe Doses of Perfluorooctane Sulfonate (PFOS): An International Collaboration - Grok Review

Key References

• PFAS profiles in biosolids, composts, and chemical fertilizers — Quebec (Canada) — ScienceDirect (2024)
• PFAS in untreated and treated biosolids from 27 U.S. and Canadian facilities — Brown and Caldwell / Water Environment Research (2025)
• PFAS in land-applied biosolids: soil accumulation, crop uptake, and dietary risk — PMC (2025/2026)
• Precursor underestimation in biosolids — PMC / Environmental Science & Technology
• PFAS in soils at ten northeastern U.S. farms — Scientific Reports (2025)
• North Carolina DEQ PFAS study of WWTPs and biosolids — NC DEQ
• Washington State PFAS in Biosolids — WA Dept. of Ecology (2025)
• EPA Draft Sewage Sludge Risk Assessment for PFOA and PFOS — EPA (January 2025)
• EPA Draft Guidance for Reducing Risk from PFOA and PFOS in Biosolids — EPA (July 2026)
• EWG: Forever chemicals may taint nearly 20 million cropland acres — EWG (2022) | Updated estimate (2025)
• Penn State Extension: Overview of PFAS and land-applied biosolids — Penn State Extension