Biosolids—the nutrient-rich material produced as a byproduct of municipal wastewater treatment—have long been applied to agricultural and forestry land as a cost-effective fertilizer and soil amendment. But biosolids also concentrate PFAS from all the inputs that enter wastewater systems: industrial discharges, urban stormwater runoff, and the full spectrum of PFAS-containing consumer products that reach wastewater treatment plants through drains, toilets, and industrial effluent. The resulting biosolids can contain thousands of nanograms of PFAS per kilogram of dry material, and decades of land application have distributed this PFAS burden across millions of acres of agricultural land in the United States, Europe, and Australia.
EPA’s First PFAS Biosolids Risk Assessment
On January 14, 2025, the EPA released its long-awaited Draft Sewage Sludge Risk Assessment for PFOA and PFOS—the first formal risk assessment of PFAS in biosolids under the Clean Water Act’s sewage sludge provisions. The draft assessed the risks from multiple pathways including direct soil ingestion, plant uptake, groundwater migration, and consumption of meat and dairy products from animals grazing on PFAS-contaminated land. The public comment period closed on August 14, 2025. The risk assessment is a necessary precursor to the establishment of numeric PFAS concentration limits for biosolids under the Clean Water Act—a step EPA has not yet taken but which the risk assessment is designed to support.
State Actions: A Patchwork of Restrictions
In the absence of federal biosolids PFAS limits, states have acted independently, creating a patchwork of restrictions that complicates wastewater management for utilities that generate biosolids across multiple state jurisdictions.
Maine enacted the nation’s most comprehensive biosolids PFAS restriction, imposing a moratorium on the land application of all biosolids and prohibiting the sale of biosolids for any purpose pending the development of safe PFAS concentration standards. The moratorium followed the discovery of widespread PFAS contamination on farms where biosolids had been applied for decades, with PFAS detected in well water, food crops, and livestock at farms in Aroostook, York, and Cumberland counties. Maine has provided financial assistance to affected farms and is developing a long-term remediation strategy.
Minnesota, effective September 2025, now requires that all biosolids intended for land application be tested for PFAS before use. Response actions—ranging from enhanced monitoring to application restrictions—are triggered based on PFAS concentration results and the proximity of application sites to drinking water sources, wetlands, and sensitive receptors. Minnesota has been particularly aggressive in this area given its history of 3M manufacturing in the Minneapolis–Saint Paul area, which contaminated groundwater and surface water with PFAS in the eastern metro region for decades.
Michigan has established numeric PFAS concentration thresholds for biosolids: application is banned when biosolids exceed specified concentrations of PFOS and PFOA, and restricted with enhanced management requirements at lower concentrations. Connecticut banned the sale of PFAS-containing biosolids for land application. Colorado, Maryland, New York, and Wisconsin have adopted monitoring requirements or use restrictions at various levels of stringency.
The Agricultural Contamination Problem
The agricultural dimension of biosolids PFAS contamination is particularly challenging because it is diffuse, long-lasting, and economically devastating for individual farm operations. PFAS applied to soil through biosolids migrate into groundwater wells used for both drinking water and irrigation, are taken up by crops (particularly leafy vegetables and root crops), and accumulate in livestock that graze or consume forage from contaminated land. Several farms in Maine, Michigan, and New Hampshire have been forced to cease operations or switch to alternative water sources after PFAS contamination was discovered in their wells and produce at concentrations that exceeded food safety guidelines.
Water Treatment Implications
The biosolids contamination pathway creates diffuse, non-point source PFAS pollution that is significantly harder to address than point-source industrial discharges. Private drinking water wells on or near former biosolids application sites require treatment solutions capable of removing PFAS at the individual household level—a market niche served by point-of-use reverse osmosis systems and certified activated carbon filters. As states expand biosolids PFAS monitoring and map historical application sites, demand for residential and small community water treatment systems will grow in affected agricultural regions. OEM filter manufacturers should track state biosolids monitoring databases to identify high-priority geographic markets where drinking water contamination from this pathway is most acute.