Landfill leachate is often viewed as a major source of PFAS in our wastewater-centric world; however, this may not be the case. Tetra Tech has conducted a mass balance analysis, quantitively accounting for inputs and outputs to and from landfills that convey PFAS to determine whether landfills are PFAS sources – as generally perceived – or if they are effectively sequestering PFAS. This Catalyst Session will go through the modeling of this mass balance and summarize the results that were discovered. This information will provide valuable insight for the industry for properly educating the public on the role that municipal solid waste landfills hold in the PFAS lifecycle.