the data include results of PFAS concentration in primary and secondary landfill leachate. Each figure in the manuscript has a specific sheet associated with it. This dataset is associated with the following publication: Robey, N., Y. Liu, T. Tolaymat, J. Bowden, H. Solo-Gabriele, and T. Townsend. Per- and Polyfluoroalkyl Substances (PFAS) Profiles in Primary and Secondary Landfill Leachates: Indications of Transformation, Liner Interactions, and other PFAS Sources. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, USA, 494: 138705, (2025).