Investigation of Sources of PFAS to the Wastewater “Sewershed”

SFEI partnered with Bay Area Clean Water Agencies (BACWA) to implement a collaborative, cost-effective, and innovative investigation of PFAS in municipal wastewater in the San Francisco Bay region. Short for per- and polyfluoroalkyl substances, PFAS (or “forever chamicals”) are a broad class of fluorine-rich compounds in many consumer and industrial products that pose significant risks to humans and wildlife.

In phase one of our study, influent (the wastewater being piped into treatment plants), effluent (the treated wastewater piped out), and biosolids were sampled from sixteen representative facilities. Samples were analyzed for PFAS using an EPA method that detects 40 target chemicals. We also looked for compounds that can break down into these target chemicals using the Total Oxidizable Precursors (TOP) method.

In phase two, we investigated major sources of PFAS to municipal wastewater by screening residential and industrial discharges within the sewersheds of seven BACWA member agencies.

Widespread PFAS in Household Wastewater

Compared to prior data, samples from wastewater showed recent declines in the concentrations of well-studied PFAS. However, we also found high levels of precursor chemicals. This suggests much higher overall concentrations of PFAS than can be measured with the EPA target analysis alone. Current methods can only quantify a fraction of the potential PFAS in samples.

Our study revealed that consumer products in homes may account for a large majority of the PFAS entering wastewater facilities. This finding can help shape state and federal strategies to reduce PFAS in wastewater, like addressing the broad uses of PFAS in household products.

We also screened industrial discharges from several businesses likely to use PFAS products or processes. At five industrial laundry facilities that mostly service restaurants and other industries, PFAS concentrations were significantly greater than levels measured in overall wastewater entering treatment facilities. We also screened discharges from hospitals, semiconductor manufacturing, and chrome plating. Most had lower levels of PFAS than the overall incoming wastewater (influent).

Next Steps

Looking forward, we will use several analytical approaches to provide even more data on the levels and types of PFAS in wastewater.

Residential and industrial laundry discharges are promising places for in-depth investigations to better understand and control PFAS in wastewater.