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PFAS and Biosolids


The Colorado Department of Public Health and Environment’s Water Quality Control Division (division) is implementing additional requirements through Regulation 64 for the beneficial use of biosolids as an interim strategy.  As of January 1, 2023, the division is requiring “preparers” of biosolids to sample and analyze biosolids for per- and polyfluoroalkyl substances (known as PFAS) and report to the division.

PFAS is an emerging contaminant of concern, and the EPA is currently conducting a risk assessment, which could lead to developing criteria for PFAS in biosolids. While the EPA is conducting their assessment, the division is taking this step of requiring sampling and analyzing biosolids for PFAS to better understand the occurrence of PFAS in biosolids in Colorado, and to mitigate risk to public health and the environment from potential adverse effects of this emerging pollutant.

The division will continue to evaluate this PFAS Interim Strategy, and it may be modified in the future.

What are biosolids? 

Biosolids are a product of domestic wastewater treatment processes. They are rich in nutrients and organic matter and farmers can use them for fertilizer and improving the quality of the soil. The Colorado Department of Public Health and Environment’s Water Quality Control Division (division) and the U.S. Environmental Protection Agency (EPA) regulate the quality and use of biosolids. The two government bodies require biosolids to undergo a treatment process and meet regulatory requirements for pathogens, pollutants, and land application to protect human health and the environment. Those processes refine the biosolids so that they can be applied to soil, which provides a stable and valuable source of plant nutrients and soil structural enhancements.

What are PFAS?? 

Per- and polyfluoroalkyl substances (PFAS) are a large group of human-made chemicals that have been widely used in industry and consumer products since the 1940s. PFAS have the ability to resist heat, water, and oil and have been used in food packaging, nonstick cookware, certain types of firefighting foam, and to make clothes, carpets, and furniture resistant to water and stains. They may also be used in certain personal care products such as shampoo, dental floss, and makeup. Creating and using these products can allow PFAS to enter our environment and wastewater. PFAS tend to break down very slowly, so they can build up in humans and animals. PFAS are associated with a range of negative health effects which include certain types of cancer, high cholesterol and reduced vaccine effectiveness. Our understanding of PFAS and the risks they may pose is rapidly evolving.

Why are we concerned about PFAS in wastewater and biosolids?

Industrial, commercial, and residential use and disposal of products containing PFAS can allow these chemicals to enter wastewater treatment facilities. As a result, researchers have found PFAS in treated wastewater and biosolids. PFAS can move in the environment and potentially impact the soil, water, and crops. Some studies have shown that certain PFAS could be harmful to human health. Therefore, we need to minimize exposure to all sources of PFAS, including drinking water and food. Given the potential human health risks associated with PFAS, it is important to improve our understanding of risks associated with the land application of biosolids. 

What steps is the division taking to understand and reduce PFAS in biosolids?

Currently, the EPA is conducting a risk-based evaluation of PFAS in biosolids.  In the meantime, the division is taking a proactive approach that focuses on measuring and understanding levels of PFAS in biosolids and identifying and reducing significant sources of PFAS migrating to wastewater treatment facilities. The division implemented the Biosolids-PFAS interim strategy on January 1, 2023, establishing monitoring requirements for biosolids preparers. This interim strategy
includes a threshold level of 50 µg/kg for one specific PFAS, perfluorooctane sulfonate (PFOS), in biosolids. In the instances where the PFOS level is = 50 µg/kg or greater, the biosolids preparer will have to develop and implement a Source Control Program to evaluate potential industrial or commercial sources of PFAS. Note that the PFOS threshold level of 50 µg/kg set by the division’s interim strategy is not a risk-based threshold. As stated above, the USEPA is currently working to complete a risk-based evaluation of PFAS in biosolids.

What can I do to reduce exposure and protect the environment?

As we use and dispose of products containing PFAS, these chemicals can enter our environment. To protect human health and the environment, manufacturers are slowly phasing out the production and use of products containing these chemicals and safer alternatives are being investigated. We encourage people to get the facts and take steps to limit their exposure from other sources. Through recent legislation, Colorado will ban the sale of certain PFAS products starting in 2024. In the meantime, if you are concerned about PFAS exposure, we recommend purchasing consumer goods and new household products that are PFAS-free. This will reduce your exposure to PFAS and prevent the chemicals from further entering our environment and water systems. We have resources on our website to help select products that are PFAS-free.



NEW: For 2024 the Colorado Department of Public Health and Environment’s Water Quality Control Division will continue to implement the “2023 Colorado Biosolids-PFAS Interim Strategy” as is without any changes through 2024. We feel that continuing to identify the extent of PFAS in biosolids is still the best approach for Colorado at this time, and will help us reduce potential risk associated with this emerging pollutant.

How to get involved



Biosolids Coordinator

For all biosolid and PFAS communications, please contact